fix(server): http error parsing on endpoints without a default response (#12927)

server/test/repositories/notification.repository.mock.ts

@@ -4,7 +4,7 @@ import { Mocked } from 'vitest';
 export const newNotificationRepositoryMock = (): Mocked<INotificationRepository> => {
   return {
     renderEmail: vitest.fn(),
-    sendEmail: vitest.fn(),
+    sendEmail: vitest.fn().mockResolvedValue({ messageId: 'message-1' }),
     verifySmtp: vitest.fn(),
   };
 };