[RFC]: Exceptions should be caught only in the `ResponseMiddleware`

[alexmerlin]

RFC

As per my brainstorming with @MarioRadu a couple of days ago:
No class (entity, repository, service etc) should treat exceptions internally without rethrowing it.
If an exception occurrs, it should be allowed to propagate until it reaches the ResponseMiddleware.php

[alexmerlin]

Implemented in #396