public function onKernelException(GetResponseForExceptionEvent $event)
    {
        $exception = $event->getException();
        
        if ($exception instanceof NotFoundHttpException) {
            $response = $event->getResponse();

            $values = array(
                'status_code' => 404,
                'message' => $exception->getMessage(),
            );
            
            $event->setResponse($this->templating->renderResponse('AlphaLemonThemeEngineBundle:Error:error.html.twig', $values, $response));
        }
    }