Throw exception when an unknown error is caught on messaging sync (#5782)

As per title for this one ;)

packages/twenty-server/src/modules/messaging/common/services/messaging-error-handling.service.ts

@@ -100,7 +100,9 @@ export class MessagingErrorHandlingService {
           messageChannel.id,
           workspaceId,
         );
-        break;
+        throw new Error(
+          `Unhandled Gmail error code ${code} with reason ${reason}`,
+        );
     }
   }