The bug is this line (wikipedia.py):

       elif self.site().has_api() and self.namespace() in [2,3] and ( '.css' in self.title() or '.js' in self.title()):

The bot username must be excluded in those title checks.

2010/3/30 emijrp <emijrp@gmail.com>
Hi;

My bot crashes while trying edit its own .css user subpages. An error requesting sysopnames['wikipedia']['es'] in user-config.py appears.

Regards!