AttributeError: 'AnonymousUser' object has no attribute 'bbb_get_attendee'

To join someone unauthenticated, Infrablue uses an AnonymusUser. The function user.get_bbb_attendee doesn't work for these.

Traceback:

  File "/home/lolo/Programmierung/Infrablue/infrablue/views.py", line 380, in post
    return self.join(user)
  File "/home/lolo/Programmierung/Infrablue/infrablue/views.py", line 388, in join
    return HttpResponseRedirect(self.meeting_bbb.join(user))
  File "/home/lolo/Programmierung/python-bigbluebutton2/bigbluebutton/django/models.py", line 249, in join
    attendee = user.bbb_get_attendee(self)
AttributeError: 'AnonymousUser' object has no attribute 'bbb_get_attendee'
[15/Jul/2020 15:09:30] "POST /meeting/join/4b1d6ea1-94ec-4e11-a7f0-fa38b01e2a7f/ HTTP/1.1" 500 102337