Deleting a User object, while that user is logged in, will yield to the user the following Exception:

A Token was not found in the SecurityContext.
500 Internal Server Error - AuthenticationCredentialsNotFoundException

This error will remain until the user manually remove the session cookie. The issue is no longer present in the eZP5 master branch.

Steps to reproduce:

1. Create a user
2. Login to front-end as that user
3. In the back-end, delete the user you've just created
4. Try to refresh/navigate on the front-end; an error will be displayed/logged.