diff --git a/.eslintrc.cjs b/.eslintrc.cjs
index 7be5a785..7d5e4573 100644
--- a/.eslintrc.cjs
+++ b/.eslintrc.cjs
@@ -5,6 +5,7 @@ module.exports = {
     'eslint:recommended',
     'plugin:@typescript-eslint/recommended',
     // 'plugin:@typescript-eslint/recommended-requiring-type-checking',
+    'plugin:@typescript-eslint/strict',
     'prettier'
   ],
   plugins: ['svelte3', 'tailwindcss', '@typescript-eslint', 'es', 'vitest'],
@@ -19,7 +20,19 @@ module.exports = {
     'package.json',
     'tsconfig.json'
   ],
-  overrides: [{ files: ['*.svelte'], processor: 'svelte3/svelte3' }],
+  overrides: [
+    { files: ['*.svelte'], processor: 'svelte3/svelte3' },
+    {
+      files: ['*.ts'],
+      extends: [
+        'eslint:recommended',
+        'plugin:@typescript-eslint/recommended',
+        'plugin:@typescript-eslint/recommended-requiring-type-checking',
+        'plugin:@typescript-eslint/strict',
+        'prettier'
+      ]
+    }
+  ],
   settings: {
     'svelte3/typescript': () => require('typescript')
   },
diff --git a/.vscode/settings.json b/.vscode/settings.json
index ff638551..925342c8 100644
--- a/.vscode/settings.json
+++ b/.vscode/settings.json
@@ -1,6 +1,6 @@
 {
   "editor.formatOnSave": true,
-  "cSpell.words": ["asyncable", "mindmap", "pako", "Serde", "serdes"],
+  "cSpell.words": ["asyncable", "KROKI", "mindmap", "pako", "Serde", "serdes", "tailwindcss"],
   "vitest.commandLine": "yarn test:unit",
   "vitest.enable": true,
   "testing.autoRun.mode": "rerun",
diff --git a/cypress/e2e/util.ts b/cypress/e2e/util.ts
index 73fe6dd2..6aa17ce5 100644
--- a/cypress/e2e/util.ts
+++ b/cypress/e2e/util.ts
@@ -17,6 +17,7 @@ export const verifyFileSize = (
 ) => {
   const fileName = `mermaid-${fileType}-2022-01-01-000000.${extension}`;
   const filePath = `${downloadsFolder}/${fileName}`;
+  // eslint-disable-next-line @typescript-eslint/no-unsafe-call
   cy.verifyDownload(fileName);
   cy.readFile(filePath, null, {
     log: false
@@ -31,6 +32,7 @@ export const verifyFileSnapshot = (
 ) => {
   const fileName = `mermaid-${fileType}-2022-01-01-000000.${extension}`;
   const filePath = `${downloadsFolder}/${fileName}`;
+  // eslint-disable-next-line @typescript-eslint/no-unsafe-call
   cy.verifyDownload(fileName);
   cy.readFile(filePath, null, {
     log: false
diff --git a/src/env.d.ts b/src/env.d.ts
index e3cf245e..8188f7aa 100644
--- a/src/env.d.ts
+++ b/src/env.d.ts
@@ -1,11 +1,11 @@
 /// <reference types="vite/client" />
 
 interface ImportMetaEnv {
-  readonly MERMAID_RENDERER_URL: string;
-  readonly MERMAID_KROKI_RENDERER_URL: string;
-  readonly MERMAID_CDN_URL: string;
-  readonly MERMAID_BASE_URL: string;
-  readonly MERMAID_LOCAL: boolean;
+  readonly MERMAID_RENDERER_URL?: string;
+  readonly MERMAID_KROKI_RENDERER_URL?: string;
+  readonly MERMAID_CDN_URL?: string;
+  readonly MERMAID_BASE_URL?: string;
+  readonly MERMAID_LOCAL?: boolean;
   // more env variables...
 }
 
diff --git a/src/global.d.ts b/src/global.d.ts
index 81ca3d20..95ecd6a0 100644
--- a/src/global.d.ts
+++ b/src/global.d.ts
@@ -9,7 +9,8 @@ declare global {
   namespace jest {
     interface Matchers<R = void>
       // eslint-disable-next-line @typescript-eslint/ban-ts-comment
-      // @ts-ignore
+      // @ts-expect-error
+      // eslint-disable-next-line no-undef
       extends TestingLibraryMatchers<typeof expect.stringContaining, R> {}
   }
 }
diff --git a/src/lib/components/actions.svelte b/src/lib/components/Actions.svelte
similarity index 90%
rename from src/lib/components/actions.svelte
rename to src/lib/components/Actions.svelte
index ed2acfd3..166a58cd 100644
--- a/src/lib/components/actions.svelte
+++ b/src/lib/components/Actions.svelte
@@ -1,6 +1,6 @@
 <script lang="ts">
   import { browser } from '$app/environment';
-  import Card from '$lib/components/card/card.svelte';
+  import Card from '$lib/components/Card/Card.svelte';
   import { env } from '$lib/util/env';
   import { pakoSerde } from '$lib/util/serde';
   import { stateStore } from '$lib/util/state';
@@ -15,8 +15,8 @@
     `mermaid-diagram-${moment().format('YYYY-MM-DD-HHmmss')}.${ext}`;
 
   const getBase64SVG = (svg?: HTMLElement, width?: number, height?: number): string => {
-    svg?.setAttribute('height', `${height}px`);
-    svg?.setAttribute('width', `${width}px`); // Workaround https://stackoverflow.com/questions/28690643/firefox-error-rendering-an-svg-image-to-html5-canvas-with-drawimage
+    height && svg?.setAttribute('height', `${height}px`);
+    width && svg?.setAttribute('width', `${width}px`); // Workaround https://stackoverflow.com/questions/28690643/firefox-error-rendering-an-svg-image-to-html5-canvas-with-drawimage
     if (!svg) {
       svg = getSvgEl();
     }
@@ -28,7 +28,10 @@
 
   const exportImage = (event: Event, exporter: Exporter) => {
     const canvas: HTMLCanvasElement = document.createElement('canvas');
-    const svg: HTMLElement = document.querySelector('#container svg');
+    const svg: HTMLElement | null = document.querySelector('#container svg');
+    if (!svg) {
+      throw new Error('svg not found');
+    }
     const box: DOMRect = svg.getBoundingClientRect();
     canvas.width = box.width;
     canvas.height = box.height;
@@ -43,6 +46,9 @@
     }
 
     const context = canvas.getContext('2d');
+    if (!context) {
+      throw new Error('context not found');
+    }
     context.fillStyle = 'white';
     context.fillRect(0, 0, canvas.width, canvas.height);
 
@@ -56,12 +62,12 @@
 
   const getSvgEl = () => {
     const svgEl: HTMLElement = document
-      .querySelector('#container svg')
+      .querySelector('#container svg')!
       .cloneNode(true) as HTMLElement;
     svgEl.setAttribute('xmlns:xlink', 'http://www.w3.org/1999/xlink');
     const fontAwesomeCdnUrl = Array.from(document.head.getElementsByTagName('link'))
       .map((l) => l.href)
-      .find((h) => h && h.includes('font-awesome'));
+      .find((h) => h.includes('font-awesome'));
     if (fontAwesomeCdnUrl == null) {
       return svgEl;
     }
@@ -99,10 +105,10 @@
       context.drawImage(image, 0, 0, canvas.width, canvas.height);
       canvas.toBlob((blob) => {
         try {
-          // @ts-ignore: https://github.com/microsoft/TypeScript-DOM-lib-generator/pull/1004/files
+          if (!blob) {
+            throw new Error('blob is empty');
+          }
           void navigator.clipboard.write([
-            /* eslint-disable no-undef */
-            // @ts-ignore: https://github.com/microsoft/TypeScript/issues/43821
             new ClipboardItem({
               [blob.type]: blob
             })
@@ -142,7 +148,7 @@
   let gistURL = '';
   stateStore.subscribe(({ loader }) => {
     if (loader?.type === 'gist') {
-      // @ts-ignore Gist will have url
+      // @ts-expect-error Gist will have url
       gistURL = loader.config.url;
     }
   });
@@ -166,8 +172,7 @@
   if (browser && ['mermaid.live', 'netlify'].some((path) => window.location.host.includes(path))) {
     isNetlify = true;
   }
-  stateStore.subscribe(async (state) => {
-    const { code, serialized } = await state;
+  stateStore.subscribe(({ code, serialized }) => {
     iUrl = `${rendererUrl}/img/${serialized}?type=png`;
     svgUrl = `${rendererUrl}/svg/${serialized}`;
     krokiUrl = `${krokiRendererUrl}/mermaid/svg/${pakoSerde.serialize(code)}`;
diff --git a/src/lib/components/card/card.svelte b/src/lib/components/Card/Card.svelte
similarity index 92%
rename from src/lib/components/card/card.svelte
rename to src/lib/components/Card/Card.svelte
index ce1c0ad7..38098eb6 100644
--- a/src/lib/components/card/card.svelte
+++ b/src/lib/components/Card/Card.svelte
@@ -1,11 +1,11 @@
 <script lang="ts">
   import type { Tab } from '$lib/types';
   import { slide } from 'svelte/transition';
-  import Tabs from './tabs.svelte';
+  import Tabs from './Tabs.svelte';
   export let isCloseable = true;
   export let isOpen = true;
   export let tabs: Tab[] = [];
-  export let activeTabID: string = '';
+  export let activeTabID = '';
   export let title: string;
   $: isOpen = isCloseable ? isOpen : true;
   $: isTabsShown = isOpen && tabs.length > 0;
diff --git a/src/lib/components/card/tabs.svelte b/src/lib/components/Card/Tabs.svelte
similarity index 100%
rename from src/lib/components/card/tabs.svelte
rename to src/lib/components/Card/Tabs.svelte
diff --git a/src/lib/components/Card/__snapshots__/card.test.ts.snap b/src/lib/components/Card/__snapshots__/card.test.ts.snap
new file mode 100644
index 00000000..c23d7e06
--- /dev/null
+++ b/src/lib/components/Card/__snapshots__/card.test.ts.snap
@@ -0,0 +1,3 @@
+// Vitest Snapshot v1
+
+exports[`card.svelte > mounts 1`] = `"<div><div class=\\"card rounded overflow-hidden m-2 flex-grow flex flex-col shadow-2xl\\"><div class=\\"bg-primary p-2 pb-0 flex-none cursor-pointer\\"><div class=\\"flex justify-between\\"><div class=\\"flex cursor-default s-lTROw8sJayZ1\\"><span class=\\"mr-2 font-semibold s-lTROw8sJayZ1\\"><i class=\\"fas fa-chevron-right icon s-lTROw8sJayZ1 isOpen\\"></i> TabTest</span> <ul class=\\"tabs s-lTROw8sJayZ1\\"><div class=\\"tab tab-lifted tab-active s-lTROw8sJayZ1\\"><i class=\\"mr-1 fab fa-git-alt s-lTROw8sJayZ1\\"></i> title1 </div><div class=\\"tab tab-lifted text-primary-content s-lTROw8sJayZ1\\"><i class=\\"mr-1 far fa-bookmark s-lTROw8sJayZ1\\"></i> title2 </div></ul></div><!--<Tabs>--> <div class=\\"flex gap-x-4 items-center -mt-2\\"></div></div></div> <div class=\\"card-body p-0 flex-grow overflow-auto text-base-content\\"></div></div><!--<Card>--></div>"`;
diff --git a/src/lib/components/card/card.test.ts b/src/lib/components/Card/card.test.ts
similarity index 81%
rename from src/lib/components/card/card.test.ts
rename to src/lib/components/Card/card.test.ts
index 764cad64..36698822 100644
--- a/src/lib/components/card/card.test.ts
+++ b/src/lib/components/Card/card.test.ts
@@ -1,6 +1,6 @@
 import { cleanup, render } from '@testing-library/svelte';
 import { describe, expect, it, afterEach } from 'vitest';
-import Card from './card.svelte';
+import Card from './Card.svelte';
 
 describe('card.svelte', () => {
   // TODO: @testing-library/svelte claims to add this automatically but it doesn't work without explicit afterEach
@@ -10,8 +10,8 @@ describe('card.svelte', () => {
     const { container } = render(Card, {
       title: 'TabTest',
       tabs: [
-        { id: 't1', title: 'title1' },
-        { id: 't2', title: 'title2' }
+        { id: 't1', title: 'title1', icon: 'fab fa-git-alt' },
+        { id: 't2', title: 'title2', icon: 'far fa-bookmark' }
       ]
     });
     expect(container).toBeTruthy();
diff --git a/src/lib/components/editor.svelte b/src/lib/components/Editor.svelte
similarity index 72%
rename from src/lib/components/editor.svelte
rename to src/lib/components/Editor.svelte
index b84683c8..5525afe9 100644
--- a/src/lib/components/editor.svelte
+++ b/src/lib/components/Editor.svelte
@@ -8,9 +8,9 @@
   import initEditor from 'monaco-mermaid';
   import { logEvent } from '$lib/util/stats';
 
-  let divEl: HTMLDivElement = null;
-  let editor: monaco.editor.IStandaloneCodeEditor;
-  let Monaco: typeof monaco;
+  let divEl: HTMLDivElement | undefined = undefined;
+  let editor: monaco.editor.IStandaloneCodeEditor | undefined;
+  let Monaco: typeof monaco | undefined;
   let editorOptions: monaco.editor.IStandaloneEditorConstructionOptions = {
     minimap: {
       enabled: false
@@ -22,7 +22,9 @@
 
   stateStore.subscribe(({ errorMarkers, editorMode, code, mermaid }) => {
     console.log('editor store subscription', { code, mermaid });
-    if (!editor) return;
+    if (!editor || !Monaco) {
+      return;
+    }
 
     // Update editor text if it's different
     const newText = editorMode === 'code' ? code : mermaid;
@@ -34,12 +36,17 @@
 
     // Update editor mode if it's different
     const language = editorMode === 'code' ? 'mermaid' : 'json';
-    if (editor.getModel().getLanguageId() !== language) {
-      Monaco?.editor.setModelLanguage(editor.getModel(), language);
+    const model = editor.getModel();
+    if (!model) {
+      console.error("editor model doesn't exist");
+      return;
+    }
+    if (model.getLanguageId() !== language) {
+      Monaco.editor.setModelLanguage(model, language);
     }
 
     // Display/clear errors
-    Monaco?.editor.setModelMarkers(editor.getModel(), 'mermaid', errorMarkers);
+    Monaco.editor.setModelMarkers(model, 'mermaid', errorMarkers);
   });
 
   themeStore.subscribe(({ isDark }) => {
@@ -60,7 +67,7 @@
     // errorDebug();
     let i = 0;
     while (i++ < 500) {
-      // @ts-ignore : This is a hack to handle a svelte-kit error when importing monaco.
+      // @ts-expect-error : This is a hack to handle a svelte-kit error when importing monaco.
       Monaco = window.monaco;
       if (Monaco !== undefined) {
         return;
@@ -72,13 +79,20 @@
 
   onMount(async () => {
     await loadMonaco(); // Fix https://github.com/mermaid-js/mermaid-live-editor/issues/175
+    if (!Monaco) {
+      throw new Error('Monaco failed to load');
+    }
+    if (!divEl) {
+      throw new Error('divEl is undefined');
+    }
+    // eslint-disable-next-line @typescript-eslint/no-unsafe-call
     initEditor(Monaco);
     errorDebug(100);
     editor = Monaco.editor.create(divEl, editorOptions);
     editor.onDidChangeModelContent(({ isFlush, changes }) => {
-      const newText = editor.getValue();
+      const newText = editor?.getValue();
       console.log('editor onDidChangeModelContent', { text, newText, isFlush, changes });
-      if (text === newText || isFlush) {
+      if (!newText || text === newText || isFlush) {
         return;
       }
       text = newText;
@@ -95,19 +109,21 @@
         });
       }
     });
-    Monaco?.editor.setTheme($themeStore.isDark ? 'mermaid-dark' : 'mermaid');
+    Monaco.editor.setTheme($themeStore.isDark ? 'mermaid-dark' : 'mermaid');
     const resizeObserver = new ResizeObserver((entries) => {
-      editor.layout({
+      editor!.layout({
         height: entries[0].contentRect.height,
         width: entries[0].contentRect.width
       });
     });
 
-    resizeObserver.observe(divEl.parentElement);
+    if (divEl.parentElement) {
+      resizeObserver.observe(divEl.parentElement);
+    }
     console.log(`editor mounted`);
     return () => {
       console.log(`editor disposed`);
-      editor.dispose();
+      editor?.dispose();
     };
   });
 </script>
diff --git a/src/lib/components/history/history.svelte b/src/lib/components/History/History.svelte
similarity index 96%
rename from src/lib/components/history/history.svelte
rename to src/lib/components/History/History.svelte
index 37527bcc..3663b71d 100644
--- a/src/lib/components/history/history.svelte
+++ b/src/lib/components/History/History.svelte
@@ -1,5 +1,5 @@
 <script lang="ts">
-  import Card from '$lib/components/card/card.svelte';
+  import Card from '$lib/components/Card/Card.svelte';
   import { inputStateStore, getStateString } from '$lib/util/state';
   import {
     addHistoryEntry,
@@ -14,7 +14,7 @@
   import { onMount } from 'svelte';
   import { get } from 'svelte/store';
   import moment from 'moment';
-  import type { HistoryType, State, Tab } from '$lib/types';
+  import type { HistoryEntry, HistoryType, State, Tab } from '$lib/types';
   import { logEvent } from '$lib/util/stats';
 
   const HISTORY_SAVE_INTERVAL = 60000;
@@ -60,7 +60,7 @@
       }
       const reader = new FileReader();
       reader.onload = (e) => {
-        const data = JSON.parse(e.target.result as string);
+        const data: HistoryEntry[] = JSON.parse(e.target.result as string);
         restoreHistory(data);
       };
       reader.readAsText(file);
diff --git a/src/lib/components/history/history.test.ts b/src/lib/components/History/history.test.ts
similarity index 82%
rename from src/lib/components/history/history.test.ts
rename to src/lib/components/History/history.test.ts
index d5a0242b..482de012 100644
--- a/src/lib/components/history/history.test.ts
+++ b/src/lib/components/History/history.test.ts
@@ -7,7 +7,7 @@ import {
   historyModeStore,
   historyStore
 } from './history';
-import { defaultState } from '../../util/state';
+import { defaultState } from '$lib/util/state';
 import { get } from 'svelte/store';
 
 describe('history', () => {
@@ -21,9 +21,9 @@ describe('history', () => {
       type: 'manual'
     });
 
-    const [manualEntry]: HistoryEntry[] = JSON.parse(
-      window.localStorage.getItem('manualHistoryStore')
-    );
+    const [manualEntry] = JSON.parse(
+      window.localStorage.getItem('manualHistoryStore') ?? '[]'
+    ) as HistoryEntry[];
 
     expect(manualEntry.time).toBe(12345);
     expect(manualEntry.type).toBe('manual');
@@ -36,7 +36,9 @@ describe('history', () => {
       type: 'auto'
     });
 
-    const [autoEntry]: HistoryEntry[] = JSON.parse(window.localStorage.getItem('autoHistoryStore'));
+    const [autoEntry] = JSON.parse(
+      window.localStorage.getItem('autoHistoryStore') ?? '[]'
+    ) as HistoryEntry[];
 
     expect(autoEntry.time).toBe(54321);
     expect(autoEntry.type).toBe('auto');
@@ -101,19 +103,23 @@ describe('history migration', () => {
       'autoHistoryStore',
       '[{"state":{"code":"graph TD\\n    A[New Year] -->|Get money| B(Go shopping)","mermaid":"{\\n  \\"theme\\": \\"dark\\"\\n}","autoSync":true,"updateDiagram":false},"time":0,"type":"auto","name":"barking-dog"},{"state":{"code":"graph TD\\n    A[Christmas] -->|Get money| B(Go shopping)","mermaid":"{\\n  \\"theme\\": \\"dark\\"\\n}","autoSync":true,"updateDiagram":true},"time":0,"type":"manual","name":"needy-mosquito"}]'
     );
-    let manualHistoryStore: HistoryEntry[] = JSON.parse(
-      window.localStorage.getItem('manualHistoryStore')
-    );
-    let autoHistoryStore: HistoryEntry[] = JSON.parse(
-      window.localStorage.getItem('autoHistoryStore')
-    );
+    let manualHistoryStore = JSON.parse(
+      window.localStorage.getItem('manualHistoryStore') ?? '[]'
+    ) as HistoryEntry[];
+    let autoHistoryStore = JSON.parse(
+      window.localStorage.getItem('autoHistoryStore') ?? '[]'
+    ) as HistoryEntry[];
     expect(manualHistoryStore.every(({ id }) => id !== undefined)).toBe(false);
     expect(autoHistoryStore.every(({ id }) => id !== undefined)).toBe(false);
 
     injectHistoryIDs();
 
-    manualHistoryStore = JSON.parse(window.localStorage.getItem('manualHistoryStore'));
-    autoHistoryStore = JSON.parse(window.localStorage.getItem('autoHistoryStore'));
+    manualHistoryStore = JSON.parse(
+      window.localStorage.getItem('manualHistoryStore') ?? '[]'
+    ) as HistoryEntry[];
+    autoHistoryStore = JSON.parse(
+      window.localStorage.getItem('autoHistoryStore') ?? '[]'
+    ) as HistoryEntry[];
     expect(manualHistoryStore.every(({ id }) => id !== undefined)).toBe(true);
     expect(autoHistoryStore.every(({ id }) => id !== undefined)).toBe(true);
   });
diff --git a/src/lib/components/history/history.ts b/src/lib/components/History/history.ts
similarity index 100%
rename from src/lib/components/history/history.ts
rename to src/lib/components/History/history.ts
diff --git a/src/lib/components/navbar.svelte b/src/lib/components/Navbar.svelte
similarity index 94%
rename from src/lib/components/navbar.svelte
rename to src/lib/components/Navbar.svelte
index 9a179bb9..3ef0a3c8 100644
--- a/src/lib/components/navbar.svelte
+++ b/src/lib/components/Navbar.svelte
@@ -1,13 +1,13 @@
-<script context="module">
+<script context="module" lang="ts">
   import { version } from 'mermaid/package.json';
   import { analytics } from '$lib/util/stats';
-  analytics?.track('version', {
+  void analytics?.track('version', {
     mermaidVersion: version
   });
 </script>
 
 <script lang="ts">
-  import Theme from './theme.svelte';
+  import Theme from './Theme.svelte';
 
   interface Link {
     title: string;
diff --git a/src/lib/components/preset.svelte b/src/lib/components/Preset.svelte
similarity index 92%
rename from src/lib/components/preset.svelte
rename to src/lib/components/Preset.svelte
index c1d466b5..ad3831ee 100644
--- a/src/lib/components/preset.svelte
+++ b/src/lib/components/Preset.svelte
@@ -1,6 +1,6 @@
 <script lang="ts">
   import { updateCode } from '$lib/util/state';
-  import Card from '$lib/components/card/card.svelte';
+  import Card from '$lib/components/Card/Card.svelte';
   import { logEvent } from '$lib/util/stats';
 
   const samples = {
@@ -104,7 +104,8 @@
       Mermaid`
   };
 
-  const loadSampleDiagram = (diagramType: string): void => {
+  type SampleTypes = keyof typeof samples;
+  const loadSampleDiagram = (diagramType: SampleTypes): void => {
     updateCode(samples[diagramType], {
       updateDiagram: true,
       resetPanZoom: true
@@ -113,8 +114,8 @@
   };
 
   // Adding in this array will add an icon to the preset menu
-  const newDiagrams: Array<keyof typeof samples> = ['Mindmap'];
-  const diagramOrder: Array<keyof typeof samples> = [
+  const newDiagrams: SampleTypes[] = ['Mindmap'];
+  const diagramOrder: SampleTypes[] = [
     'Sequence',
     'Flow',
     'Class',
diff --git a/src/lib/components/theme.svelte b/src/lib/components/Theme.svelte
similarity index 94%
rename from src/lib/components/theme.svelte
rename to src/lib/components/Theme.svelte
index 2e860077..ba35753e 100644
--- a/src/lib/components/theme.svelte
+++ b/src/lib/components/Theme.svelte
@@ -1,4 +1,4 @@
-<script>
+<script lang="ts">
   import { setTheme, themeStore } from '$lib/util/theme';
 
   const themes = [
@@ -52,7 +52,7 @@
     <!-- svelte-ignore a11y-no-noninteractive-tabindex -->
     <ul tabindex="0" class="p-4 menu compact">
       {#each themes as theme}
-        <li class={theme.includes($themeStore.theme) ? 'bordered' : ''}>
+        <li class:bordered={$themeStore.theme !== undefined && theme.includes($themeStore.theme)}>
           <span
             class="btn btn-ghost justify-start"
             on:click={() => setTheme(theme)}
diff --git a/src/lib/components/view.svelte b/src/lib/components/View.svelte
similarity index 87%
rename from src/lib/components/view.svelte
rename to src/lib/components/View.svelte
index dc5cfc6d..28fa976f 100644
--- a/src/lib/components/view.svelte
+++ b/src/lib/components/View.svelte
@@ -6,6 +6,7 @@
   import { logEvent } from '$lib/util/stats';
   import { AsyncQueue, cmdKey } from '$lib/util/util';
   import { render as renderDiagram } from '$lib/util/mermaid';
+  import type { MermaidConfig } from 'mermaid';
 
   let code = '';
   let config = '';
@@ -16,9 +17,12 @@
   let hide = false;
   let manualUpdate = true;
   let panZoomEnabled = $stateStore.panZoom;
-  let pzoom: SvgPanZoom.Instance;
+  let pzoom: typeof panzoom | undefined;
 
   const handlePanZoomChange = () => {
+    if (!pzoom) {
+      return;
+    }
     const pan = pzoom.getPan();
     const zoom = pzoom.getZoom();
     updateCodeStore({ pan, zoom });
@@ -32,8 +36,11 @@
     hide = true;
     pzoom?.destroy();
     pzoom = undefined;
-    Promise.resolve().then(() => {
+    void Promise.resolve().then(() => {
       const graphDiv = document.getElementById('graph-div');
+      if (!graphDiv) {
+        return;
+      }
       pzoom = panzoom(graphDiv, {
         onPan: handlePanZoomChange,
         onZoom: handlePanZoomChange,
@@ -70,10 +77,10 @@
         code = state.code;
         config = state.mermaid;
         panZoomEnabled = state.panZoom;
-        const scroll = view.parentElement.scrollTop;
+        const scroll = view.parentElement!.scrollTop;
         delete container.dataset.processed;
         await renderDiagram(
-          Object.assign({}, JSON.parse(state.mermaid)),
+          Object.assign({}, JSON.parse(state.mermaid)) as MermaidConfig,
           code,
           'graph-div',
           (svgCode, bindFunctions) => {
@@ -82,6 +89,9 @@
               container.innerHTML = svgCode;
               // console.log(container.innerHTML);
               const graphDiv = document.getElementById('graph-div');
+              if (!graphDiv) {
+                throw new Error('graph-div not found');
+              }
               graphDiv.setAttribute('height', '100%');
               graphDiv.style.maxWidth = '100%';
               if (bindFunctions) {
@@ -90,7 +100,7 @@
             }
           }
         );
-        view.parentElement.scrollTop = scroll;
+        view.parentElement!.scrollTop = scroll;
         error = false;
       } else if (manualUpdate) {
         manualUpdate = false;
@@ -106,8 +116,8 @@
   const q = new AsyncQueue(handleStateChange);
 
   onMount(() => {
-    stateStore.subscribe(async (state) => {
-      await q.process(state);
+    stateStore.subscribe((state) => {
+      void q.process(state);
     });
     window.addEventListener('resize', () => {
       if ($stateStore.panZoom && pzoom) {
diff --git a/src/lib/components/card/__snapshots__/card.test.ts.snap b/src/lib/components/card/__snapshots__/card.test.ts.snap
deleted file mode 100644
index eb662c95..00000000
--- a/src/lib/components/card/__snapshots__/card.test.ts.snap
+++ /dev/null
@@ -1,3 +0,0 @@
-// Vitest Snapshot v1
-
-exports[`card.svelte > mounts 1`] = `"<div><div class=\\"card rounded overflow-hidden m-2 flex-grow flex flex-col shadow-2xl\\"><div class=\\"bg-primary p-2 pb-0 flex-none cursor-pointer\\"><div class=\\"flex justify-between\\"><div class=\\"flex cursor-default s-_wx1E_JHsCoF\\"><span class=\\"mr-2 font-semibold s-_wx1E_JHsCoF\\"><i class=\\"fas fa-chevron-right icon s-_wx1E_JHsCoF isOpen\\"></i> TabTest</span> <ul class=\\"tabs s-_wx1E_JHsCoF\\"><div class=\\"tab tab-lifted tab-active s-_wx1E_JHsCoF\\"><i class=\\"mr-1 undefined s-_wx1E_JHsCoF\\"></i> title1 </div><div class=\\"tab tab-lifted text-primary-content s-_wx1E_JHsCoF\\"><i class=\\"mr-1 undefined s-_wx1E_JHsCoF\\"></i> title2 </div></ul></div><!--<Tabs>--> <div class=\\"flex gap-x-4 items-center -mt-2\\"></div></div></div> <div class=\\"card-body p-0 flex-grow overflow-auto text-base-content\\"></div></div><!--<Card>--></div>"`;
diff --git a/src/lib/types.d.ts b/src/lib/types.d.ts
index 30f94b9c..d4617890 100644
--- a/src/lib/types.d.ts
+++ b/src/lib/types.d.ts
@@ -73,14 +73,24 @@ export type HistoryEntry = { id: string; state: State; time: number; url?: strin
     }
 );
 
-export interface DocConfig {
-  [key: string]: {
+export type DocConfig = Record<
+  string,
+  {
     code: string;
     config?: string;
-  };
-}
+  }
+>;
 
 export type EditorMode = 'code' | 'config';
 
 export type Loader = (url: string) => Promise<State>;
 export type Optional<T, K extends keyof T> = Pick<Partial<T>, K> & Omit<T, K>;
+
+export interface ErrorHash {
+  loc: {
+    first_line: number;
+    last_line: number;
+    first_column: number;
+    last_column: number;
+  };
+}
diff --git a/src/lib/util/fileLoaders/gist.ts b/src/lib/util/fileLoaders/gist.ts
index f2cb7ed9..58ff85ea 100644
--- a/src/lib/util/fileLoaders/gist.ts
+++ b/src/lib/util/fileLoaders/gist.ts
@@ -3,17 +3,23 @@
 /* eslint-disable @typescript-eslint/no-unsafe-member-access */
 /* eslint-disable @typescript-eslint/no-explicit-any */
 import type { State } from '$lib/types';
-import { defaultState } from '../state';
-import { addHistoryEntry } from '../../components/history/history';
+import { defaultState } from '$lib/util/state';
+import { addHistoryEntry } from '$lib/components/History/history';
 
 const codeFileName = 'code.mmd';
 const configFileName = 'config.json';
 
+interface GithubFile {
+  truncated: boolean;
+  raw_url: string;
+  content: string;
+}
+
 const isValidGist = (files: any): boolean => {
   return codeFileName in files;
 };
 
-const getFileContent = async (file: any): Promise<string> => {
+const getFileContent = async (file: GithubFile): Promise<string> => {
   if (file.truncated) {
     return await (await fetch(file.raw_url)).text();
   }
@@ -29,16 +35,26 @@ interface GistData {
   url: string;
 }
 
+interface GistResponse {
+  files: Record<string, GithubFile>;
+  html_url: string;
+  history: { url: string; committed_at: string; version: string; user: { login: string } }[];
+}
+
 const getGistData = async (gistURL: string): Promise<GistData> => {
+  const path = gistURL.split('github.com').pop();
+  if (!path) {
+    throw new Error('Invalid GitHub URL' + gistURL);
+  }
   // eslint-disable-next-line @typescript-eslint/no-unused-vars
-  const [_, __, gistID, revisionID] = gistURL.split('github.com').pop().split('/');
+  const [_, __, gistID, revisionID] = path.split('/');
   // eslint-disable-next-line @typescript-eslint/no-unsafe-assignment
-  const { html_url, files, history } = await (
+  const { html_url, files, history }: GistResponse = await (
     await fetch(`https://api.github.com/gists/${gistID}${revisionID ? '/' + revisionID : ''}`)
   ).json();
   if (isValidGist(files)) {
     const code = await getFileContent(files[codeFileName]);
-    let config: string;
+    let config = '{}';
     if (configFileName in files) {
       config = await getFileContent(files[configFileName]);
     }
@@ -50,10 +66,10 @@ const getGistData = async (gistURL: string): Promise<GistData> => {
       config,
       author: currentItem.user.login,
       time: new Date(currentItem.committed_at).getTime(),
-      version: (currentItem.version as string).slice(-7)
+      version: currentItem.version.slice(-7)
     };
   } else {
-    throw 'Invalid gist provided';
+    throw new Error('Invalid gist provided');
   }
 };
 
@@ -73,35 +89,38 @@ const getStateFromGist = (gist: GistData, gistURL: string = gist.url): State =>
 };
 
 export const loadGistData = async (gistURL: string): Promise<State> => {
-  try {
-    // eslint-disable-next-line @typescript-eslint/no-unused-vars
-    const [_, __, gistID, revisionID] = gistURL.split('github.com').pop().split('/');
-    // eslint-disable-next-line @typescript-eslint/no-unsafe-assignment
-    const { history } = await (
-      await fetch(`https://api.github.com/gists/${gistID}${revisionID ? '/' + revisionID : ''}`)
-    ).json();
-    const gistHistory: GistData[] = [];
-    for (const entry of history) {
-      // eslint-disable-next-line @typescript-eslint/no-unsafe-assignment
-      const data: GistData = await getGistData(entry.url).catch(() => undefined);
-      data && gistHistory.push(data);
-    }
-    if (gistHistory.length === 0) {
-      throw 'Invalid gist provided';
-    }
-    gistHistory.reverse();
-    const state = getStateFromGist(gistHistory.slice(-1).pop(), gistURL);
-    for (const gist of gistHistory) {
-      addHistoryEntry({
-        state: getStateFromGist(gist),
-        time: gist.time,
-        type: 'loader',
-        url: gist.url,
-        name: `${gist.author} v${gist.version}`
-      });
-    }
-    return state;
-  } catch (err) {
-    console.error(err);
+  const path = gistURL.split('github.com').pop();
+  if (!path) {
+    throw new Error('Invalid GitHub URL' + gistURL);
   }
+  // eslint-disable-next-line @typescript-eslint/no-unused-vars
+  const [_, __, gistID, revisionID] = path.split('/');
+  // eslint-disable-next-line @typescript-eslint/no-unsafe-assignment
+  const { history }: GistResponse = await (
+    await fetch(`https://api.github.com/gists/${gistID}${revisionID ? '/' + revisionID : ''}`)
+  ).json();
+  const gistHistory: GistData[] = [];
+  for (const entry of history) {
+    const data: GistData | undefined = await getGistData(entry.url).catch(() => undefined);
+    data && gistHistory.push(data);
+  }
+  if (gistHistory.length === 0) {
+    throw new Error('Invalid gist provided');
+  }
+  gistHistory.reverse();
+  const entry = gistHistory.slice(-1).pop();
+  if (!entry) {
+    throw new Error('Invalid gist provided');
+  }
+  const state = getStateFromGist(entry, gistURL);
+  for (const gist of gistHistory) {
+    addHistoryEntry({
+      state: getStateFromGist(gist),
+      time: gist.time,
+      type: 'loader',
+      url: gist.url,
+      name: `${gist.author} v${gist.version}`
+    });
+  }
+  return state;
 };
diff --git a/src/lib/util/fileLoaders/loader.ts b/src/lib/util/fileLoaders/loader.ts
index e40a988f..596d02a2 100644
--- a/src/lib/util/fileLoaders/loader.ts
+++ b/src/lib/util/fileLoaders/loader.ts
@@ -8,10 +8,11 @@ const loaders: Record<string, Loader> = {
 export const loadDataFromUrl = async (): Promise<void> => {
   const searchParams = new URLSearchParams(window.location.search);
   let state: Partial<State> = defaultState;
-  let code: string, config: string;
+  let code: string | undefined = undefined;
+  let config: string | undefined = undefined;
   let loaded = false;
-  const codeURL: string = searchParams.get('code');
-  const configURL: string = searchParams.get('config');
+  const codeURL: string | undefined = searchParams.get('code') ?? undefined;
+  const configURL: string | undefined = searchParams.get('config') ?? undefined;
 
   if (codeURL) {
     code = await (await fetch(codeURL)).text();
@@ -23,9 +24,6 @@ export const loadDataFromUrl = async (): Promise<void> => {
     config = defaultState.mermaid;
   }
   if (!code) {
-    // eslint-disable-next-line @typescript-eslint/ban-ts-comment
-    // @ts-ignore
-    // eslint-disable-next-line @typescript-eslint/no-unsafe-call
     for (const [key, value] of searchParams.entries()) {
       if (key in loaders) {
         try {
@@ -38,6 +36,9 @@ export const loadDataFromUrl = async (): Promise<void> => {
       }
     }
   } else {
+    if (!codeURL) {
+      throw new Error('Code URL is not defined');
+    }
     state = {
       code,
       mermaid: config,
diff --git a/src/lib/util/mermaid.ts b/src/lib/util/mermaid.ts
index d6697928..f4d09e72 100644
--- a/src/lib/util/mermaid.ts
+++ b/src/lib/util/mermaid.ts
@@ -23,5 +23,5 @@ export const render = async (
 
 export const parse = async (code: string): Promise<boolean> => {
   await init();
-  return (await mermaid.parseAsync(code)) as boolean;
+  return await mermaid.parseAsync(code);
 };
diff --git a/src/lib/util/migrations.test.ts b/src/lib/util/migrations.test.ts
index 4b1f79a4..8c7a3a28 100644
--- a/src/lib/util/migrations.test.ts
+++ b/src/lib/util/migrations.test.ts
@@ -16,18 +16,22 @@ describe('migrations', () => {
   it('should migrate from v0 to v1', async () => {
     const { applyMigrations } = await import('./migrations');
     let manualHistoryStore: HistoryEntry[] = JSON.parse(
-      window.localStorage.getItem('manualHistoryStore')
-    );
+      window.localStorage.getItem('manualHistoryStore') ?? '[]'
+    ) as HistoryEntry[];
     let autoHistoryStore: HistoryEntry[] = JSON.parse(
-      window.localStorage.getItem('autoHistoryStore')
-    );
+      window.localStorage.getItem('autoHistoryStore') ?? '[]'
+    ) as HistoryEntry[];
     expect(manualHistoryStore.every(({ id }) => id !== undefined)).toBe(false);
     expect(autoHistoryStore.every(({ id }) => id !== undefined)).toBe(false);
 
     applyMigrations();
 
-    manualHistoryStore = JSON.parse(window.localStorage.getItem('manualHistoryStore'));
-    autoHistoryStore = JSON.parse(window.localStorage.getItem('autoHistoryStore'));
+    manualHistoryStore = JSON.parse(
+      window.localStorage.getItem('manualHistoryStore') ?? '[]'
+    ) as HistoryEntry[];
+    autoHistoryStore = JSON.parse(
+      window.localStorage.getItem('autoHistoryStore') ?? '[]'
+    ) as HistoryEntry[];
     expect(manualHistoryStore.every(({ id }) => id !== undefined)).toBe(true);
     expect(autoHistoryStore.every(({ id }) => id !== undefined)).toBe(true);
   });
diff --git a/src/lib/util/migrations.ts b/src/lib/util/migrations.ts
index f739bda6..7851270b 100644
--- a/src/lib/util/migrations.ts
+++ b/src/lib/util/migrations.ts
@@ -1,13 +1,13 @@
 import { writable, get, type Writable } from 'svelte/store';
 import { persist, localStorage } from '$lib/util/persist';
-import { injectHistoryIDs } from '$lib/components/history/history';
+import { injectHistoryIDs } from '$lib/components/History/history';
 import { logEvent } from './stats';
 
 interface MigrationState {
   version: number;
 }
 
-const migrations: { [key: string]: () => void } = {
+const migrations: Record<string, () => void> = {
   injectHistoryIDs
 };
 
diff --git a/src/lib/util/persist.ts b/src/lib/util/persist.ts
index cf032b89..31aeba3f 100644
--- a/src/lib/util/persist.ts
+++ b/src/lib/util/persist.ts
@@ -39,16 +39,16 @@ let noWarnings = false;
 /**
  * List of storages where the warning have already been displayed.
  */
-const alreadyWarnFor: Array<string> = [];
+const alreadyWarnFor: string[] = [];
 
 /**
  * Add a log to indicate that the requested Storage have not been found.
  * @param {string} storageName
  */
-const warnStorageNotFound = (storageName) => {
-  const isProduction = typeof process !== 'undefined' && process.env?.NODE_ENV === 'production';
+const warnStorageNotFound = (storageName: string) => {
+  const isProduction = typeof process !== 'undefined' && process.env.NODE_ENV === 'production';
 
-  if (!noWarnings && alreadyWarnFor.indexOf(storageName) === -1 && !isProduction) {
+  if (!noWarnings && !alreadyWarnFor.includes(storageName) && !isProduction) {
     let message = `Unable to find the ${storageName}. No data will be persisted.`;
     if (typeof window === 'undefined') {
       message +=
@@ -60,17 +60,8 @@ const warnStorageNotFound = (storageName) => {
   }
 };
 
-const allowedClasses = [];
-/**
- * Add a class to the allowed list of classes to be serialized
- * @param classDef The class to add to the list
- */
-export const addSerializableClass = (classDef: () => unknown): void => {
-  allowedClasses.push(classDef);
-};
-
 const serialize = (value: unknown): string => ESSerializer.serialize(value);
-const deserialize = (value: string): unknown => {
+const deserialize = (value?: string | null): unknown => {
   // @TODO: to remove in the next major
   if (value === 'undefined') {
     return undefined;
@@ -78,7 +69,7 @@ const deserialize = (value: string): unknown => {
 
   if (value !== null && value !== undefined) {
     try {
-      return ESSerializer.deserialize(value, allowedClasses);
+      return ESSerializer.deserialize(value);
     } catch (e) {
       // Do nothing
       // use the value "as is"
@@ -162,7 +153,7 @@ export function persist<T>(
     store.set(initialValue);
   }
 
-  if ((storage as SelfUpdateStorageInterface<T>).addListener) {
+  if ('addListener' in storage) {
     (storage as SelfUpdateStorageInterface<T>).addListener(key, (newValue) => {
       store.set(newValue);
     });
@@ -184,7 +175,7 @@ function getBrowserStorage(
   browserStorage: Storage,
   listenExternalChanges = false
 ): SelfUpdateStorageInterface<any> {
-  const listeners: Array<{ key: string; listener: (newValue: any) => void }> = [];
+  const listeners: { key: string; listener: (newValue: any) => void }[] = [];
   const listenerFunction = (event: StorageEvent) => {
     const eventKey = event.key;
     if (event.storageArea === browserStorage) {
@@ -196,12 +187,14 @@ function getBrowserStorage(
     }
   };
   const connect = () => {
-    if (listenExternalChanges && typeof window !== 'undefined' && window?.addEventListener) {
+    // eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
+    if (listenExternalChanges && typeof window !== 'undefined' && window.addEventListener) {
       window.addEventListener('storage', listenerFunction);
     }
   };
   const disconnect = () => {
-    if (listenExternalChanges && typeof window !== 'undefined' && window?.removeEventListener) {
+    // eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
+    if (listenExternalChanges && typeof window !== 'undefined' && window.removeEventListener) {
       window.removeEventListener('storage', listenerFunction);
     }
   };
@@ -237,10 +230,11 @@ function getBrowserStorage(
 
 /**
  * Storage implementation that use the browser local storage
- * @param {boolean} listenExternalChanges - Update the store if the localStorage is updated from another page
+ * @param listenExternalChanges - Update the store if the localStorage is updated from another page
  */
 export function localStorage<T>(listenExternalChanges = false): StorageInterface<T> {
-  if (typeof window !== 'undefined' && window?.localStorage) {
+  // eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
+  if (typeof window !== 'undefined' && window.localStorage) {
     return getBrowserStorage(window.localStorage, listenExternalChanges);
   }
   warnStorageNotFound('window.localStorage');
@@ -250,7 +244,7 @@ export function localStorage<T>(listenExternalChanges = false): StorageInterface
 /**
  * Storage implementation that do nothing
  */
-export function noopStorage(): StorageInterface<any> {
+export function noopStorage<T>(): StorageInterface<T> {
   return {
     getValue(): null {
       return null;
diff --git a/src/lib/util/serde.ts b/src/lib/util/serde.ts
index 3d2df939..5dbffa1b 100644
--- a/src/lib/util/serde.ts
+++ b/src/lib/util/serde.ts
@@ -36,7 +36,7 @@ const serdes: { [key in SerdeType]: Serde } = {
 };
 
 export const serializeState = (state: State, serde: SerdeType = 'pako'): string => {
-  if (serdes[serde] === undefined) {
+  if (!(serde in serdes)) {
     throw new Error(`Unknown serde type: ${serde}`);
   }
   const json = JSON.stringify(state);
diff --git a/src/lib/util/state.ts b/src/lib/util/state.ts
index 39337655..b0c9a3ba 100644
--- a/src/lib/util/state.ts
+++ b/src/lib/util/state.ts
@@ -5,7 +5,9 @@ import { serializeState, deserializeState } from './serde';
 import { cmdKey, errorDebug, AsyncQueue } from './util';
 import { parse } from './mermaid';
 
-import type { MarkerData, State, ValidatedState } from '$lib/types';
+import type { ErrorHash, MarkerData, State, ValidatedState } from '$lib/types';
+import type { MermaidConfig } from 'mermaid';
+
 export const defaultState: State = {
   code: `graph TD
     A[Christmas] -->|Get money| B(Go shopping)
@@ -50,7 +52,7 @@ export const currentState: ValidatedState = (() => {
   };
 })();
 
-let q: AsyncQueue<State>;
+let q: AsyncQueue<State> | undefined;
 
 const processState = async (state: State) => {
   const processed: ValidatedState = {
@@ -69,14 +71,19 @@ const processState = async (state: State) => {
     processed.error = e;
     errorDebug();
     console.error(e);
-    if (e.hash) {
+    if ('hash' in e) {
+      const {
+        loc: { first_line, last_line, first_column, last_column }
+        // eslint-disable-next-line @typescript-eslint/no-unsafe-member-access
+      } = e.hash as ErrorHash;
       try {
         const marker: MarkerData = {
           severity: 8, // Error
-          startLineNumber: e.hash.loc.first_line,
-          startColumn: e.hash.loc.first_column,
-          endLineNumber: e.hash.loc.last_line,
-          endColumn: (e.hash.loc.last_column as number) + 1,
+          startLineNumber: first_line,
+          startColumn: first_column,
+          endLineNumber: last_line,
+          endColumn: last_column + 1,
+          // eslint-disable-next-line @typescript-eslint/no-unsafe-member-access, @typescript-eslint/no-unsafe-assignment
           message: e.str
         };
         processed.errorMarkers = [marker];
@@ -99,7 +106,7 @@ export const stateStore: Readable<ValidatedState> = derived(
         set(newState);
       });
     }
-    q.process(state);
+    void q.process(state);
   },
   currentState
 );
@@ -109,8 +116,10 @@ export const loadState = (data: string): void => {
   console.log(`Loading '${data}'`);
   try {
     state = deserializeState(data);
-    const mermaidConfig: { [key: string]: string } =
-      typeof state.mermaid === 'string' ? JSON.parse(state.mermaid) : state.mermaid;
+    const mermaidConfig: MermaidConfig =
+      typeof state.mermaid === 'string'
+        ? (JSON.parse(state.mermaid) as MermaidConfig)
+        : state.mermaid;
     if (
       mermaidConfig.securityLevel &&
       mermaidConfig.securityLevel !== 'strict' &&
@@ -180,7 +189,7 @@ export const updateConfig = (config: string): void => {
 
 export const toggleDarkTheme = (dark: boolean): void => {
   inputStateStore.update((state) => {
-    const config = JSON.parse(state.mermaid);
+    const config = JSON.parse(state.mermaid) as MermaidConfig;
     if (!config.theme || ['dark', 'default'].includes(config.theme)) {
       config.theme = dark ? 'dark' : 'default';
     }
@@ -194,7 +203,7 @@ export const initURLSubscription = (): void => {
   stateStore.subscribe(({ serialized }) => {
     clearTimeout(urlDebounce);
     urlDebounce = window.setTimeout(() => {
-      history.replaceState(undefined, undefined, `#${serialized}`);
+      history.replaceState(undefined, '', `#${serialized}`);
     }, 250);
   });
 };
diff --git a/src/lib/util/stats.ts b/src/lib/util/stats.ts
index b86405ce..c349088d 100644
--- a/src/lib/util/stats.ts
+++ b/src/lib/util/stats.ts
@@ -1,6 +1,6 @@
 import { browser } from '$app/environment';
 import type { AnalyticsInstance } from 'analytics';
-export let analytics: AnalyticsInstance;
+export let analytics: AnalyticsInstance | undefined;
 
 export const initAnalytics = async (): Promise<void> => {
   if (browser && !analytics) {
@@ -27,7 +27,7 @@ export const initAnalytics = async (): Promise<void> => {
   }
 };
 
-export const detectType = (text: string): string => {
+export const detectType = (text: string): string | undefined => {
   const possibleDiagramTypes = [
     'classDiagram',
     'erDiagram',
@@ -49,7 +49,7 @@ export const detectType = (text: string): string => {
 };
 
 export const countLines = (code: string): number => {
-  return (code.match(/\n/g) || '').length + 1;
+  return (code.match(/\n/g)?.length ?? 0) + 1;
 };
 
 export const saveStatistics = (graph: string): void => {
@@ -80,19 +80,20 @@ const delaysPerEvent = {
   themeChange: defaultDelay
 };
 export type AnalyticsEvent = keyof typeof delaysPerEvent;
-const timeouts: Record<string, number> = {};
+const timeouts: Map<string, number> = new Map<string, number>();
 // manual debounce to reduce the number of events sent to analytics
 export const logEvent = (name: AnalyticsEvent, data?: unknown): void => {
   if (!analytics) {
     return;
   }
   const key = data ? JSON.stringify({ name, data }) : name;
-  if (timeouts[key] === undefined) {
+  if (!timeouts.has(key)) {
     void analytics.track(name, data);
   } else {
-    clearTimeout(timeouts[key]);
+    clearTimeout(timeouts.get(key));
   }
-  timeouts[key] = window.setTimeout(() => {
-    delete timeouts[key];
-  }, delaysPerEvent[name]);
+  timeouts.set(
+    key,
+    window.setTimeout(() => timeouts.delete(key), delaysPerEvent[name])
+  );
 };
diff --git a/src/lib/util/util.ts b/src/lib/util/util.ts
index 7eeb64c9..980bda63 100644
--- a/src/lib/util/util.ts
+++ b/src/lib/util/util.ts
@@ -23,10 +23,10 @@ export const initHandler = async (): Promise<void> => {
   syncDiagram();
   initURLSubscription();
   await initAnalytics();
-  analytics?.page();
+  await analytics?.page();
 };
 
-export const isMac = navigator.platform.toUpperCase().indexOf('MAC') >= 0;
+export const isMac = navigator.platform.toUpperCase().includes('MAC');
 export const cmdKey = isMac ? 'Cmd' : 'Ctrl';
 
 let count = 0;
diff --git a/src/routes/+layout.svelte b/src/routes/+layout.svelte
index 4c14fe93..099537f6 100644
--- a/src/routes/+layout.svelte
+++ b/src/routes/+layout.svelte
@@ -10,8 +10,8 @@
   // This can be removed once https://github.com/sveltejs/kit/issues/1612 is fixed.
   // Then move it into src and vite will bundle it automatically.
   onMount(() => {
-    window.addEventListener('hashchange', async (ev) => {
-      await initHandler();
+    window.addEventListener('hashchange', () => {
+      void initHandler();
     });
     if ('serviceWorker' in navigator) {
       navigator.serviceWorker
diff --git a/src/routes/edit/+page.svelte b/src/routes/edit/+page.svelte
index e3977afa..ae92d28d 100644
--- a/src/routes/edit/+page.svelte
+++ b/src/routes/edit/+page.svelte
@@ -1,11 +1,11 @@
 <script lang="ts">
-  import Editor from '$lib/components/editor.svelte';
-  import Navbar from '$lib/components/navbar.svelte';
-  import Preset from '$lib/components/preset.svelte';
-  import Actions from '$lib/components/actions.svelte';
-  import View from '$lib/components/view.svelte';
-  import Card from '$lib/components/card/card.svelte';
-  import History from '$lib/components/history/history.svelte';
+  import Editor from '$lib/components/Editor.svelte';
+  import Navbar from '$lib/components/Navbar.svelte';
+  import Preset from '$lib/components/Preset.svelte';
+  import Actions from '$lib/components/Actions.svelte';
+  import View from '$lib/components/View.svelte';
+  import Card from '$lib/components/Card/Card.svelte';
+  import History from '$lib/components/History/History.svelte';
   import { inputStateStore, stateStore, updateCodeStore } from '$lib/util/state';
   import { cmdKey, initHandler, syncDiagram } from '$lib/util/util';
   import { onMount } from 'svelte';
@@ -86,6 +86,10 @@
     await initHandler();
     const resizer = document.getElementById('resizeHandler');
     const element = document.getElementById('editorPane');
+    if (!resizer || !element) {
+      console.debug('Failed to find resize handler or editor pane', { resizer, element });
+      return;
+    }
     const resize = (e: { pageX: number }) => {
       const newWidth = e.pageX - element.getBoundingClientRect().left;
       if (newWidth > 50) {
diff --git a/src/routes/view/+page.svelte b/src/routes/view/+page.svelte
index 8de80023..936fc0d1 100644
--- a/src/routes/view/+page.svelte
+++ b/src/routes/view/+page.svelte
@@ -1,5 +1,5 @@
 <script lang="ts">
-  import View from '$lib/components/view.svelte';
+  import View from '$lib/components/View.svelte';
   import { initHandler } from '$lib/util/util';
   import { onMount } from 'svelte';
   onMount(initHandler);
diff --git a/tsconfig.json b/tsconfig.json
index 38b29b7f..91263b2e 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -12,6 +12,7 @@
   "compilerOptions": {
     "resolveJsonModule": true,
     "allowSyntheticDefaultImports": true,
+    "strictNullChecks": true,
     "types": ["vitest/importMeta"]
   },
   "extends": "./.svelte-kit/tsconfig.json"