no argument type-hinted as "container" (Symfony 3.4)

[tacman]

I'm getting the following error with Symfony 3.4:

Invalid service "atolye15_slack_exception.listener": method "Atolye15\SlackExceptionBundle\EventListener\ExceptionListener::__construct()" has no argument type-hinted as "container". Check your service definition.

I imagine this is because of auto-wiring or private services or something like that, but don't know enough about how services are defined to fix this.