public function process(ServerRequestInterface $request, RequestHandlerInterface $handler): ResponseInterface
    {
        $errorPageConfig = Config::getInstance()->get('errorPage');
        $controllerClass = '\\app\\Controllers\\' . $errorPageConfig[0];
        $route = new Route('404', $errorPageConfig[0], $errorPageConfig[1]);
        $controller = new $controllerClass($route, $request);
        $response = new Response;
        ob_start();
        $controller->execute();
        $responseController = ob_get_clean();
        $response->getBody()->write($responseController);
        $response = $response->withStatus(404);
        $logger = new Logger();
        $logger->info('Error 404, NotFoundMiddleware');
        return $response;
    }