feat(validators): add check for non-existent userId

- The `UserGuard` now checks whether the `userId` extracted from the token exists.
- If the `userId` does not exist, an error is logged and a response with the 'Unauthorized' status is returned.

Signed-off-by: Mathis <yidhra@tuta.io>

src/validators/UserGuard.ts

@@ -27,6 +27,10 @@ async function UserGuard(req: Request, res: Response, next: NextFunction) {
 	if (token) {
 		// @ts-ignore
 		const userId = token.sub;
+		if (!userId) {
+			logger.error(USER_NOT_EXIST);
+			return res.status(UNAUTHORIZED).json({message: USER_NOT_EXIST});
+		}
     const user= await MySqlService.User.getById(DbHandler, userId);
     if (user) {
 			logger.info(`An user do a request. (${user?.username})`)