Treat unauthenticated exceptions the same as everything else

app/Exceptions/Handler.php

@@ -231,7 +231,7 @@ class Handler extends ExceptionHandler
     protected function unauthenticated($request, AuthenticationException $exception)
     {
         if ($request->expectsJson()) {
-            return response()->json(['error' => 'Unauthenticated.'], 401);
+            return response()->json(self::convertToArray($exception), 401);
         }
 
         return redirect()->guest(route('auth.login'));