Code review comment for lp:~ronnie.vd.c/loco-team-portal/623288

I get the following when clicking the iCal icon next to team events on the main page.

Traceback:
File "/usr/lib/pymodules/python2.6/django/core/handlers/base.py" in get_response
  100. response = callback(request, *callback_args, **callback_kwargs)
File "/home/chris/Dropbox/Projects/loco-directory/current/loco_directory/events/views.py" in teams_event_list_ical
  78. return event_list_ical(TeamEvent.objects.all(), 'All Ubuntu LoCo Team Events')
File "/home/chris/Dropbox/Projects/loco-directory/current/loco_directory/events/views.py" in event_list_ical
  55. response.write(calendar.serialize())
File "/usr/lib/pymodules/python2.6/vobject/base.py" in serialize
  186. return behavior.serialize(self, buf, lineLength, validate)
File "/usr/lib/pymodules/python2.6/vobject/behavior.py" in serialize
  157. out = base.defaultSerialize(transformed, buf, lineLength)
File "/usr/lib/pymodules/python2.6/vobject/base.py" in defaultSerialize
  947. child.serialize(outbuf, lineLength, validate=False)
File "/usr/lib/pymodules/python2.6/vobject/base.py" in serialize
  186. return behavior.serialize(self, buf, lineLength, validate)
File "/usr/lib/pymodules/python2.6/vobject/behavior.py" in serialize
  157. out = base.defaultSerialize(transformed, buf, lineLength)
File "/usr/lib/pymodules/python2.6/vobject/base.py" in defaultSerialize
  947. child.serialize(outbuf, lineLength, validate=False)
File "/usr/lib/pymodules/python2.6/vobject/base.py" in serialize
  186. return behavior.serialize(self, buf, lineLength, validate)
File "/usr/lib/pymodules/python2.6/vobject/behavior.py" in serialize
  157. out = base.defaultSerialize(transformed, buf, lineLength)
File "/usr/lib/pymodules/python2.6/vobject/base.py" in defaultSerialize
  953. if obj.behavior and not startedEncoded: obj.behavior.encode(obj)
File "/usr/lib/pymodules/python2.6/vobject/icalendar.py" in encode
  609. line.value = backslashEscape(line.value)
File "/usr/lib/pymodules/python2.6/vobject/base.py" in backslashEscape
  1137. s=s.replace("\\","\\\\").replace(";","\;").replace(",","\,")

Exception Type: AttributeError at /events/team/ical/
Exception Value: 'NoneType' object has no attribute 'replace'