Deliver failed Symfony messenger messages to Sentry

services.yaml

services:
  Sentry\FlushableClientInterface: '@Sentry\ClientInterface'

WorkerSubscriber.php

<?php declare(strict_types=1);

namespace App\Subscriber;

use Sentry\FlushableClientInterface;
use Symfony\Component\EventDispatcher\EventSubscriberInterface;
use Symfony\Component\Messenger\Event\WorkerMessageFailedEvent;
use Symfony\Component\Messenger\Exception\HandlerFailedException;

class WorkerSubscriber implements EventSubscriberInterface
{
    private FlushableClientInterface $client;

    /**
     * @param FlushableClientInterface $client
     */
    public function __construct(FlushableClientInterface $client)
    {
        $this->client = $client;
    }

    public function onWorkerMessageFailed(WorkerMessageFailedEvent $event): void
    {
        if ($event->willRetry()) {
            // Only capture the hard fails.
            return;
        }

        $error = $event->getThrowable();

        if ($error instanceof HandlerFailedException) {
            $error = $error->getPrevious();
        }

        $this->client->captureException($error);

        // Flush normally happens at shutdown... which never happens in the worker.
        $this->client->flush();
    }

    public static function getSubscribedEvents(): array
    {
        return [
            WorkerMessageFailedEvent::class => 'onWorkerMessageFailed',
        ];
    }
}