Refactor tests and improve error handling across various services

- Updated `useAuth` tests to use async functions for JSON responses to avoid promise resolution issues.
- Changed `AdminBrandManager` tests to use `mockImplementation` for consistent mock behavior.
- Enhanced `ProfileManager.Authenticated` tests to ensure proper error handling and assertions for partial updates.
- Modified `SystemCheck` tests to prevent memory leaks by using `mockImplementation` for API calls.
- Improved error handling in `ai.routes.ts` by refining validation schemas and adding error extraction utility.
- Updated `auth.routes.test.ts` to inject mock logger for better error tracking.
- Refined `flyer.routes.ts` to ensure proper validation and error handling for flyer ID parameters.
- Enhanced `admin.db.ts` to ensure specific errors are re-thrown for better error management.
- Updated `budget.db.test.ts` to improve mock behavior and ensure accurate assertions.
- Refined `flyer.db.ts` to improve error handling for race conditions during store creation.
- Enhanced `notification.db.test.ts` to ensure specific error types are tested correctly.
- Updated `recipe.db.test.ts` to ensure proper handling of not found errors.
- Improved `user.db.ts` to ensure consistent error handling for user retrieval.
- Enhanced `flyerProcessingService.server.test.ts` to ensure accurate assertions on transformed data.
- Updated `logger.server.ts` to disable transport in test environments to prevent issues.
- Refined `queueService.workers.test.ts` to ensure accurate mocking of email service.
- Improved `userService.test.ts` to ensure proper mock implementations for repository classes.
- Enhanced `checksum.test.ts` to ensure reliable file content creation in tests.
- Updated `pdfConverter.test.ts` to reset shared state objects and mock implementations before each test.

src/services/db/user.db.ts

@@ -178,11 +178,12 @@ export class UserRepository {
         'SELECT user_id, email, password_hash FROM public.users WHERE user_id = $1',
         [userId]
       );
-      if (res.rowCount === 0) {
+      if ((res.rowCount ?? 0) === 0) {
         throw new NotFoundError(`User with ID ${userId} not found.`);
       }
       return res.rows[0];
     } catch (error) {
+      if (error instanceof NotFoundError) throw error;
       logger.error({ err: error, userId }, 'Database error in findUserWithPasswordHashById');
       throw new Error('Failed to retrieve user with sensitive data by ID from database.');
     }
@@ -366,7 +367,7 @@ export class UserRepository {
         'SELECT user_id, email FROM public.users WHERE refresh_token = $1',
         [refreshToken]
       );
-      if (res.rowCount === 0) {
+      if ((res.rowCount ?? 0) === 0) {
         throw new NotFoundError('User not found for the given refresh token.');
       }
       return res.rows[0];