Symfony inject EntityManager in LogoutListener

Question

Using Symfony 3.4, I need to do persist user before logout, so I've implemented the following listener:

<?php
namespace c975L\UserBundle\Listeners;

use Doctrine\ORM\EntityManagerInterface;
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\Security\Core\Authentication\Token\TokenInterface;
use Symfony\Component\Security\Http\Logout\LogoutHandlerInterface;
use c975L\UserBundle\Entity\User;

class LogoutListener implements LogoutHandlerInterface
{
    private $em;

    public function __construct(EntityManagerInterface $em)
    {
        $this->em = $em;
    }

    public function logout(Request $request, Response $response, TokenInterface $token)
    {
        $user = $token->getUser();
        if ($user instanceof User) {
            $user->setLatestSignout(new \DateTime());
            $this->em->persist($user);
            $this->em->flush();
        }
    }
}

I have autowired in services.yml

services:
    _defaults:
        autowire: true
        autoconfigure: true
        public: true
    c975L\UserBundle\Listeners\:
        resource: '../../Listeners/*'

but I receive the following compilation error

Compile Error: ContainerNxlf3ac\appDevDebugProjectContainer::load(): Failed opening required '/.../var/cache/dev/ContainerNxlf3ac/getLogoutlistener2Service.php' (include_path='.:/usr/share/php')

It looks like I have to alias the service but I can't manage to do so...

I have the same result when using parent::__construct();

Error doesn't appear if __construct() is removed but then $this->em is not defined...

[EDIT - Added firewall part]

security.yml

firewalls:
    dev:
        pattern: ^/(_(profiler|wdt)|css|fonts|images|js)/
        security: false
    main:
        pattern: ^/
        provider: c975_l_userbundle
        form_login:
            login_path: user_signin
            check_path: user_signin
            default_target_path: user_dashboard
            csrf_token_generator: security.csrf.token_manager
        remember_me:
            secret: '%secret%'
            lifetime: 31536000
            path: /
            secure: true
        anonymous:    true
        logout_on_user_change: true
        logout:
            path: user_signout
            handlers: [c975L\UserBundle\Listeners\Logoutlistener]

Answer 1

The problem was in the firewall part. It was a mistake using a "l" (lowercase) in place of a "L" (uppercase) for LogoutListener name. Setting the following worked.

handlers: [c975L\UserBundle\Listeners\LogoutListener]

[EDIT] There was a bug, that has been solved by https://github.com/symfony/symfony/pull/26355