Type error when using str(user) on a player with null name

[Luc1412]

There are some cases when players neither got a EpicGames name nor an external auth name. (eg. for darkxdrift1242)

This causes a problem with str(user): TypeError: __str__ returned non-string (type NoneType). I believe this is an unexpected error. Maybe a string 'null' or 'none' might be better.