Enforce type checking in CI (#4126)

# Description of Changes
Currently, the `tsconfig.json` file enforces strict type checking, but
nothing in CI checks that the code is actually correctly typed. [Vite
only transpiles TypeScript
code](https://vite.dev/guide/features.html#transpile-only) so doesn't
ensure that the TS code we're running is correct.

This PR adds running of the type checker to CI and fixes the type errors
that have already crept into the codebase.

Note that many of the changes I've made to 'fix the types' are just
using `any` to disable the type checker because the code is under too
much churn to fix anything properly at the moment. I still think
enabling the type checker now is the best course of action though
because otherwise we'll never be able to fix all of them, and it should
at least help us not break things when adding new code.

Co-authored-by: James <[email protected]>

frontend/src/utils/thumbnailUtils.ts

@@ -6,9 +6,9 @@ import { getDocument } from "pdfjs-dist";
  */
 export function calculateScaleFromFileSize(fileSize: number): number {
   const MB = 1024 * 1024;
-  
+
   if (fileSize < 1 * MB) return 0.6;      // < 1MB: High quality
-  if (fileSize < 5 * MB) return 0.4;      // 1-5MB: Medium-high quality  
+  if (fileSize < 5 * MB) return 0.4;      // 1-5MB: Medium-high quality
   if (fileSize < 15 * MB) return 0.3;     // 5-15MB: Medium quality
   if (fileSize < 30 * MB) return 0.2;     // 15-30MB: Low-medium quality
   return 0.15;                            // 30MB+: Low quality
@@ -182,43 +182,41 @@ export async function generateThumbnailForFile(file: File): Promise<string | und
     console.log('File is not a PDF or image, generating placeholder:', file.name);
     return generatePlaceholderThumbnail(file);
   }
-  
+
+  // Calculate quality scale based on file size
+  console.log('Generating thumbnail for', file.name);
+  const scale = calculateScaleFromFileSize(file.size);
+  console.log(`Using scale ${scale} for ${file.name} (${(file.size / 1024 / 1024).toFixed(1)}MB)`);
   try {
-    console.log('Generating thumbnail for', file.name);
-    
-    // Calculate quality scale based on file size
-    const scale = calculateScaleFromFileSize(file.size);
-    console.log(`Using scale ${scale} for ${file.name} (${(file.size / 1024 / 1024).toFixed(1)}MB)`);
-    
     // Only read first 2MB for thumbnail generation to save memory
     const chunkSize = 2 * 1024 * 1024; // 2MB
     const chunk = file.slice(0, Math.min(chunkSize, file.size));
     const arrayBuffer = await chunk.arrayBuffer();
-    
-    const pdf = await getDocument({ 
+
+    const pdf = await getDocument({
       data: arrayBuffer,
       disableAutoFetch: true,
       disableStream: true
     }).promise;
-    
+
     const page = await pdf.getPage(1);
     const viewport = page.getViewport({ scale }); // Dynamic scale based on file size
     const canvas = document.createElement("canvas");
     canvas.width = viewport.width;
     canvas.height = viewport.height;
     const context = canvas.getContext("2d");
-    
+
     if (!context) {
       throw new Error('Could not get canvas context');
     }
-    
+
     await page.render({ canvasContext: context, viewport }).promise;
     const thumbnail = canvas.toDataURL();
-    
+
     // Immediately clean up memory after thumbnail generation
     pdf.destroy();
     console.log('Thumbnail generated and PDF destroyed for', file.name);
-    
+
     return thumbnail;
   } catch (error) {
     if (error instanceof Error) {
@@ -227,27 +225,27 @@ export async function generateThumbnailForFile(file: File): Promise<string | und
         // Return a placeholder or try with full file instead of chunk
         try {
           const fullArrayBuffer = await file.arrayBuffer();
-          const pdf = await getDocument({ 
+          const pdf = await getDocument({
             data: fullArrayBuffer,
             disableAutoFetch: true,
             disableStream: true,
             verbosity: 0 // Reduce PDF.js warnings
           }).promise;
-          
+
           const page = await pdf.getPage(1);
           const viewport = page.getViewport({ scale });
           const canvas = document.createElement("canvas");
           canvas.width = viewport.width;
           canvas.height = viewport.height;
           const context = canvas.getContext("2d");
-          
+
           if (!context) {
             throw new Error('Could not get canvas context');
           }
-          
+
           await page.render({ canvasContext: context, viewport }).promise;
           const thumbnail = canvas.toDataURL();
-          
+
           pdf.destroy();
           return thumbnail;
         } catch (fallbackError) {
@@ -262,4 +260,4 @@ export async function generateThumbnailForFile(file: File): Promise<string | und
     console.warn('Unknown error generating thumbnail for', file.name, error);
     return undefined;
   }
-}
+}