PdoHelper fails if username / password are NULL
By default the username and password passed to the PDO backend are NULL because SQLite does not need a username / password in our case.
The recent refactoring in the static object container now detects that NULL is passed to the PDO backend but a string is expected:
#1283859777: Tried to create instance of class F3\FLOW3\Utility\PdoHelper without passing constructor argument $user in Packages/Framework/FLOW3/Classes/Persistence/Backend/GenericPdo/Backend.php line 122
This error is triggered when no Objects.db exists and the backend tries to create one.