Entering a faulty address manually throws:

  Traceback (most recent call last):
  File "/home/johnrob/server/tornado/web.py", line 988, in _execute
    getattr(self, self.request.method.lower())(*args, **kwargs)
  File "chat.py", line 33, in post
    self.do_post()
  File "chat.py", line 104, in do_post
    lat, lon, zip = placefinder.address_to_lat_lon(address)
  File "/home/johnrob/server/placefinder.py", line 9, in address_to_lat_lon
    lat = dom.getElementsByTagName('latitude')[0].childNodes[0].nodeValue
  IndexError: list index out of range

GeoIP would be a nice addition for browsers that don't share the location.