IndexController.php

<?php
declare(strict_types = 1);

namespace App\Controller;

use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\Routing\Annotation\Route;
use Throwable;

class IndexController
{
    /**
     * Default application response when requested root.
     *
     * @Route(
     *      path="/",
     *      methods={"GET"}
     *  )
     *
     * @throws Throwable
     */
    public function __invoke(): Response
    {
        return new Response('', Response::HTTP_OK);
    }
}