add default unauthenticated stub method

src/Illuminate/Foundation/Exceptions/Handler.php

@@ -205,6 +205,20 @@ protected function prepareException(Exception $e)
         return $e;
     }
 
+    /**
+     * Convert an authentication exception into a response.
+     *
+     * @param  \Illuminate\Http\Request  $request
+     * @param  \Illuminate\Auth\AuthenticationException  $exception
+     * @return \Illuminate\Http\Response
+     */
+    protected function unauthenticated($request, AuthenticationException $exception)
+    {
+        return $request->expectsJson()
+                    ? response()->json(['message' => 'Unauthenticated.'], 401)
+                    : redirect()->guest(route('login'));
+    }
+
     /**
      * Create a response object from the given validation exception.
      *