Creative window hook can't handle empty slots

[MostAwesomeDude]

Traceback (most recent call last):
  File "/home/simpsoco/local/local/lib/python2.7/site-packages/twisted/python/log.py", line 84, in callWithLogger
    return callWithContext({"system": lp}, func, *args, **kw)
  File "/home/simpsoco/local/local/lib/python2.7/site-packages/twisted/python/log.py", line 69, in callWithContext
    return context.call({ILogContext: newCtx}, func, *args, **kw)
  File "/home/simpsoco/local/local/lib/python2.7/site-packages/twisted/python/context.py", line 118, in callWithContext
    return self.currentContext().callWithContext(ctx, func, *args, **kw)
  File "/home/simpsoco/local/local/lib/python2.7/site-packages/twisted/python/context.py", line 81, in callWithContext
    return func(*args,**kw)
--- <exception caught here> ---
  File "/home/simpsoco/local/local/lib/python2.7/site-packages/twisted/internet/posixbase.py", line 614, in _doReadOrWrite
    why = selectable.doRead()
  File "/home/simpsoco/local/local/lib/python2.7/site-packages/twisted/internet/tcp.py", line 203, in doRead
    return self._dataReceived(data)
  File "/home/simpsoco/local/local/lib/python2.7/site-packages/twisted/internet/tcp.py", line 209, in _dataReceived
    rval = self.protocol.dataReceived(data)
  File "/home/simpsoco/bravo/bravo/beta/protocol.py", line 349, in dataReceived
    self.handlers[header](payload)
  File "/home/simpsoco/bravo/bravo/beta/protocol.py", line 1179, in wcreative
    container.secondary, container.count)
exceptions.AttributeError: 'Container' object has no attribute 'secondary'

This is caused by the creative inventory object not being able to deal with an emptied-out slot.