Clean up and improve non-gitea js error filter (#37148) (#37155)

Backport #37148 by @silverwind

1. Filter out errors that contain `chrome-extension://` etc protocols
2. Extract filtering into its own function and test it
3. Fix the `window.config.assetUrlPrefix` mock, guaranteed to end with
`/assets`
4. Remove useless `??` and `?.` for properties that always exist

---
This PR was written with the help of Claude Opus 4.6

Co-authored-by: silverwind <me@silverwind.io>
Co-authored-by: Claude (Opus 4.6) <noreply@anthropic.com>

web_src/js/modules/errors.test.ts

@@ -1,4 +1,19 @@
-import {showGlobalErrorMessage} from './errors.ts';
+import {isGiteaError, showGlobalErrorMessage} from './errors.ts';
+
+test('isGiteaError', () => {
+  expect(isGiteaError('', '')).toBe(true);
+  expect(isGiteaError('moz-extension://abc/content.js', '')).toBe(false);
+  expect(isGiteaError('safari-extension://abc/content.js', '')).toBe(false);
+  expect(isGiteaError('safari-web-extension://abc/content.js', '')).toBe(false);
+  expect(isGiteaError('chrome-extension://abc/content.js', '')).toBe(false);
+  expect(isGiteaError('https://other-site.com/script.js', '')).toBe(false);
+  expect(isGiteaError('http://localhost:3000/some/page', '')).toBe(true);
+  expect(isGiteaError('http://localhost:3000/assets/js/index.abc123.js', '')).toBe(true);
+  expect(isGiteaError('', `Error\n    at chrome-extension://abc/content.js:1:1`)).toBe(false);
+  expect(isGiteaError('', `Error\n    at https://other-site.com/script.js:1:1`)).toBe(false);
+  expect(isGiteaError('', `Error\n    at http://localhost:3000/assets/js/index.abc123.js:1:1`)).toBe(true);
+  expect(isGiteaError('http://localhost:3000/assets/js/index.js', `Error\n    at chrome-extension://abc/content.js:1:1`)).toBe(false);
+});
 
 test('showGlobalErrorMessage', () => {
   document.body.innerHTML = '<div class="page-content"></div>';

web_src/js/modules/errors.ts

@@ -23,11 +23,19 @@ export function showGlobalErrorMessage(msg: string, msgType: Intent = 'error') {
   msgContainer.prepend(msgDiv);
 }
 
+// Detect whether an error originated from Gitea's own scripts, not from
+// browser extensions or other external scripts.
+const extensionRe = /(chrome|moz|safari(-web)?)-extension:\/\//;
+export function isGiteaError(filename: string, stack: string): boolean {
+  if (extensionRe.test(filename) || extensionRe.test(stack)) return false;
+  const assetBaseUrl = new URL(`${window.config.assetUrlPrefix}/`, window.location.origin).href;
+  if (filename && !filename.startsWith(assetBaseUrl) && !filename.startsWith(window.location.origin)) return false;
+  if (stack && !stack.includes(assetBaseUrl)) return false;
+  return true;
+}
+
 export function processWindowErrorEvent({error, reason, message, type, filename, lineno, colno}: ErrorEvent & PromiseRejectionEvent) {
   const err = error ?? reason;
-  const assetBaseUrl = String(new URL(`${window.config?.assetUrlPrefix ?? '/assets'}/`, window.location.origin));
-  const {runModeIsProd} = window.config ?? {};
-
   // `error` and `reason` are not guaranteed to be errors. If the value is falsy, it is likely a
   // non-critical event from the browser. We log them but don't show them to users. Examples:
   // - https://developer.mozilla.org/en-US/docs/Web/API/ResizeObserver#observation_errors
@@ -35,12 +43,11 @@ export function processWindowErrorEvent({error, reason, message, type, filename,
   // - https://github.com/go-gitea/gitea/issues/20240
   if (!err) {
     if (message) console.error(new Error(message));
-    if (runModeIsProd) return;
+    if (window.config.runModeIsProd) return;
   }
 
-  // If the error stack trace does not include the base URL of our script assets, it likely came
-  // from a browser extension or inline script. Do not show such errors in production.
-  if (err instanceof Error && !err.stack?.includes(assetBaseUrl) && runModeIsProd) return;
+  // Filter out errors from browser extensions or other non-Gitea scripts.
+  if (!isGiteaError(filename ?? '', err?.stack ?? '')) return;
 
   let msg = err?.message ?? message;
   if (lineno) msg += ` (${filename} @ ${lineno}:${colno})`;

web_src/js/vitest.setup.ts

@@ -13,7 +13,7 @@ await import('./globals.ts');
 window.config = {
   appUrl: 'http://localhost:3000/',
   appSubUrl: '',
-  assetUrlPrefix: '',
+  assetUrlPrefix: '/assets',
   sharedWorkerUri: '',
   runModeIsProd: true,
   customEmojis: {},