如何在自定义PHP MVC中创建页面404错误？

// 控制器文件
class HomeController {
    public function notFound() {
        http_response_code(404);
        require_once 'views/404.php';
    }
}

// 路由配置文件
$routes = [
    '/' => 'HomeController@index',
    '/about' => 'HomeController@about',
    // 其他路由规则...
    '404' => 'HomeController@notFound'
];

// 入口文件
$requestUrl = $_SERVER['REQUEST_URI'];
$route = trim(parse_url($requestUrl, PHP_URL_PATH), '/');
if (array_key_exists($route, $routes)) {
    $controllerAction = explode('@', $routes[$route]);
    $controller = new $controllerAction[0];
    $action = $controllerAction[1];
    $controller->$action();
} else {
    $controller = new HomeController();
    $controller->notFound();
}