fix(app): repair theme CSS sync persistence and data loss (#2067)

fluxer_app/src/features/theme/state/ThemeLibrary.ts

@@ -125,6 +125,7 @@ class ThemeLibrary {
 	localFiles: Array<ThemeLibraryLocalFileReference> = [];
 	enabledThemeIds: Array<string> = [];
 	isHydrated = false;
+	loadFailed = false;
 	isBusy = false;
 	revision = 0;
 	private initPromise: Promise<void> | null = null;
@@ -173,12 +174,13 @@ class ThemeLibrary {
 				this.localFiles = localFiles.sort((a, b) => a.name.localeCompare(b.name));
 				this.enabledThemeIds = enabledThemeIds.filter((id) => themes.some((theme) => theme.id === id));
 				this.isHydrated = true;
+				this.loadFailed = false;
 				this.revision += 1;
 			});
 		} catch (error) {
 			logger.error('Failed to hydrate theme library', error);
 			runInAction(() => {
-				this.isHydrated = true;
+				this.loadFailed = true;
 			});
 		}
 	}

fluxer_app/src/features/theme/utils/ThemeLibraryDb.ts

@@ -94,7 +94,7 @@ function getDatabase(): Promise<IDBDatabase> {
 	if (openPromise) {
 		return openPromise;
 	}
-	openPromise = new Promise((resolve, reject) => {
+	const promise = new Promise<IDBDatabase>((resolve, reject) => {
 		if (!browserIndexedDB) {
 			reject(new Error('IndexedDB unavailable'));
 			return;
@@ -126,7 +126,13 @@ function getDatabase(): Promise<IDBDatabase> {
 		request.onerror = () => reject(request.error ?? new Error('Failed to open theme library database'));
 		request.onblocked = () => reject(new Error('Theme library database upgrade is blocked by another window'));
 	});
-	return openPromise;
+	promise.catch(() => {
+		if (openPromise === promise) {
+			openPromise = null;
+		}
+	});
+	openPromise = promise;
+	return promise;
 }
 
 async function withReadonlyDb<T>(