Grass seems broken.

[mike]

The following traceback comes up when adding grass via ige.

2010-06-15 23:31:27-0400 [Broker,client] Peer will receive following PB tracebac
k:
2010-06-15 23:31:27-0400 [Broker,client] Unhandled Error
        Traceback (most recent call last):
          File "f:\Projects\Twisted\trunk\twisted\spread\banana.py", line 148, i
n gotItem
            self.callExpressionReceived(item)
          File "f:\Projects\Twisted\trunk\twisted\spread\banana.py", line 111, i
n callExpressionReceived
            self.expressionReceived(obj)
          File "f:\Projects\Twisted\trunk\twisted\spread\pb.py", line 514, in ex
pressionReceived
            method(*sexp[1:])
          File "f:\Projects\Twisted\trunk\twisted\spread\pb.py", line 828, in pr
oto_cachemessage
            self._recvMessage(self.cachedLocallyAs, requestID, objectID, message
, answerRequired, netArgs, netKw)
        --- <exception caught here> ---
          File "f:\Projects\Twisted\trunk\twisted\spread\pb.py", line 840, in _r
ecvMessage
            netResult = object.remoteMessageReceived(self, message, netArgs, net
Kw)
          File "F:\Projects\MV3D\branches\420-isguitime\mv3d\net\pb.py", line 65
2, in remoteMessageReceived
            kw)
          File "F:\Projects\Twisted\trunk\twisted\spread\flavors.py", line 422,
in remoteMessageReceived
            state = apply(method, args, kw)
          File "F:\Projects\MV3D\branches\420-isguitime\mv3d\client\view\visual.
py", line 1119, in observe_setHeightRange
            layer = self.grass.getLayer(layer)
        exceptions.AttributeError: 'NoneType' object has no attribute 'getLayer'

[mike]

This seems to produce the error that Zenex reported where the terrain disappeared after editing it.