Add cause to "spell check loading failed" error (#22923)

GitOrigin-RevId: 37772c842bb9d92200c08fa7ce89ec0b85fe1b94

services/web/frontend/js/features/source-editor/hunspell/HunspellManager.ts

@@ -160,9 +160,14 @@ export class HunspellManager {
     } else if (rest.loaded) {
       this.loaded = true
     } else if (rest.loadingFailed) {
-      captureException(new Error('Spell check loading failed'), {
-        tags: { ol_spell_check_language: this.language },
-      })
+      captureException(
+        new Error('Spell check loading failed', {
+          cause: rest.loadingFailed,
+        }),
+        {
+          tags: { ol_spell_check_language: this.language },
+        }
+      )
       this.loadingFailed = true
       this.pendingMessages.length = 0
     }

services/web/frontend/js/features/source-editor/hunspell/hunspell.worker.ts

@@ -171,7 +171,7 @@ self.addEventListener('message', async event => {
         self.postMessage({ loaded: true })
       } catch (error) {
         console.error(error)
-        self.postMessage({ loadingFailed: true })
+        self.postMessage({ loadingFailed: error })
       }
       break