Add minimum length check for username in UserServiceUsernameTaken fun…

…ction

src/functions/user/services/user/username-taken.ts

@@ -6,6 +6,7 @@ export type UserServiceUsernameTakenProps = Required<Pick<User, "username">>;
 export const UserServiceUsernameTaken = async ({
   username,
 }: UserServiceUsernameTakenProps) => {
+  if (username.length < 4) return { usernameTaken: true };
   const usernameTaken = await UserModel.findOne({ username }).lean();
   return { usernameTaken: !!usernameTaken };
 };