symfony: [DI] ServiceContainer build error after upgrading to 4.1.4

Exception trace: Symfony\Component\DependencyInjection\Dumper\PhpDumper->dumpValue() at /var/www/html/vendor/symfony/dependency-injection/Dumper/PhpDumper.php:614 Symfony\Component\DependencyInjection\Dumper\PhpDumper->addServiceMethodCalls() at /var/www/html/vendor/symfony/dependency-injection/Dumper/PhpDumper.php:516 Symfony\Component\DependencyInjection\Dumper\PhpDumper->addServiceInlinedDefinitions() at /var/www/html/vendor/symfony/dependency-injection/Dumper/PhpDumper.php:792 Symfony\Component\DependencyInjection\Dumper\PhpDumper->addService() at /var/www/html/vendor/symfony/dependency-injection/Dumper/PhpDumper.php:827 Symfony\Component\DependencyInjection\Dumper\PhpDumper->addServices() at /var/www/html/vendor/symfony/dependency-injection/Dumper/PhpDumper.php:194 Symfony\Component\DependencyInjection\Dumper\PhpDumper->dump() at /var/www/html/vendor/symfony/http-kernel/Kernel.php:704 Symfony\Component\HttpKernel\Kernel->dumpContainer() at /var/www/html/vendor/symfony/http-kernel/Kernel.php:541 Symfony\Component\HttpKernel\Kernel->initializeContainer() at /var/www/html/vendor/symfony/http-kernel/Kernel.php:123 Symfony\Component\HttpKernel\Kernel->boot() at /var/www/html/vendor/symfony/framework-bundle/Console/Application.php:65 Symfony\Bundle\FrameworkBundle\Console\Application->doRun() at /var/www/html/vendor/symfony/console/Application.php:145 Symfony\Component\Console\Application->run() at /var/www/html/bin/console:39

namespace App\Monolog;

use Doctrine\ORM\EntityManagerInterface;
use Monolog\Handler\AbstractProcessingHandler;

class DoctrineDBHandler extends AbstractProcessingHandler
{
    private $entityManager;

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

    protected function write(array $record): void
    {
        // write log to db
    }
}

namespace App\EventSubscriber;

use Doctrine\Common\EventSubscriber;
use Doctrine\ORM\Event\LifecycleEventArgs;
use Monolog\Logger;

class DoctrineLogSubscriber implements EventSubscriber
{
    private $logger;

    public function __construct(Logger $logger)
    {
        $this->logger = $logger;
    }

    public function getSubscribedEvents(): array
    {
        return ['postPersist'];
    }

    public function postPersist(LifecycleEventArgs $args): void
    {
        $this->logger->addInfo('create');
    }
}

parameters:
    locale: 'en'

services:
    _defaults:
        autowire: true
        autoconfigure: true
        public: false

    App\:
        resource: '../src/*'
        exclude: '../src/{DependencyInjection,Entity,Migrations,Tests,Kernel.php}'

    App\DoctrineLogSubscriber:
        arguments: ['@monolog.logger.demo']
        tags:
            - { name: doctrine.event_subscriber }

...
monolog:
    channels: ['demo']
    handlers:
        main:
            type: stream
            path: "%kernel.logs_dir%/%kernel.environment%.log"
            level: debug
            channels: ["!event"]
        console:
            type: console
            process_psr_3_messages: false
            channels: ["!event", "!doctrine", "!console"]
        demo:
            channels: ['demo']
            level: INFO
            type: service
            id: App\Monolog\DoctrineDBHandler