Symfony version(s) affected: 4.3

Description
Not finding an Entity via @ParamConverter makes the phpunit test fail if project is created with symfony/skeleton.

How to reproduce
I have built 2 projects ParamConverterPass and ParamConverterFail to help reproduce the problem.

The problem is that if we use @ParamConverter to get a non-existing entity, with Doctrine, using data in url, it will make the phpunit test fail if the project is built with symfony/skeleton.

Even if both projects return 404, the one built with symfony/skeletonis not catched by phpunit and return "Sorry, the page you are looking for could not be found." while the one built with symfony/website-skeleton return "App\Entity\Player object not found by the @ParamConverter annotation."

Possible Solution
Haven't got time to investigate yet

Additional context