crash on normalized_of about conceptnet5 HOT 3 CLOSED

Traceback (most recent call last):
  File "/srv/conceptnet5/env/lib/python2.6/site-packages/flask/app.py", line 1518, in __call__
    return self.wsgi_app(environ, start_response)
  File "/srv/conceptnet5/env/lib/python2.6/site-packages/flask/app.py", line 1506, in wsgi_app
    response = self.make_response(self.handle_exception(e))
  File "/srv/conceptnet5/env/lib/python2.6/site-packages/flask/app.py", line 1504, in wsgi_app
    response = self.full_dispatch_request()
  File "/srv/conceptnet5/env/lib/python2.6/site-packages/flask/app.py", line 1264, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/srv/conceptnet5/env/lib/python2.6/site-packages/flask/app.py", line 1262, in full_dispatch_request
    rv = self.dispatch_request()
  File "/srv/conceptnet5/env/lib/python2.6/site-packages/flask/app.py", line 1248, in dispatch_request
    return self.view_functions[rule.endpoint](**req.view_args)
  File "/srv/conceptnet5/conceptnet5/api.py", line 39, in get_data
    json[label] = f(uri)
  File "/srv/conceptnet5/conceptnet5/api.py", line 189, in get_normalized_of
    json[-1]['url'] = root_url + json[-1]['uri']
TypeError: 'NoneType' object is unsubscriptable