[Security] [Firewall] Bug fixed in SimplePreAuthenticationListener when createToken() not return TokenInterface object

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | no
| Fixed tickets | 
| License       | MIT
| Doc PR        | 
Your welcome! Don't forget to [squash you PR](http://symfony.com/doc/current/contributing/code/patches.html#rework-your-patch)