title: Problem using the API Mercure with Symfony
body: <p>Here is the <em><strong>error message</strong></em> :
  Argument 1 passed to App\Controller\PublisherController::index() must be an instance of Symfony\Component\Mercure\Publisher, instance of Symfony\Component\Mercure\Debug\TraceablePublisher given, called in /home/gw01/Etna/PLI/vendor/symfony/http-kernel/HttpKernel.php on line 145 (500 Internal Server Error)</p>
  <p><strong>PublisherController :</strong></p>
  <pre><code>&lt;?php
  
  namespace App\Controller;
  
  use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;
  use Symfony\Component\HttpFoundation\Request;
  use Symfony\Component\HttpFoundation\Response;
  use Symfony\Component\Mercure\Publisher;
  use Symfony\Component\Mercure\Update;
  use Symfony\Component\Routing\Annotation\Route;
  
  /**
   * Class PublisherController
   * @package App\Controller
   */
  class PublisherController extends AbstractController
  {
      /**
       * @Route(&quot;/publish/{topic}&quot;, name=&quot;publisher&quot;, methods={&quot;POST&quot;})
       */
      public function index(Publisher $publisher, $topic, Request $request)
      {
          $publisher(new Update($topic, $request-&gt;getContent()));
          return new Response('success');
      }
  }
  </code></pre>
  <p><strong>How can i <strong>fix</strong> this</strong> ?</p>