update JSON error message

app/Exceptions/Handler.php

@@ -52,7 +52,7 @@ class Handler extends ExceptionHandler
     protected function unauthenticated($request, AuthenticationException $exception)
     {
         return $request->expectsJson()
-                    ? response()->json(['error' => 'Unauthenticated.'], 401)
+                    ? response()->json(['message' => 'Unauthenticated.'], 401)
                     : redirect()->guest(route('login'));
     }
 }