Commit 303 removed an implicit check againt NoneType. Restore it explicitely.

git-svn-id: https://svn.erp5.org/repos/neo/branches/prototype3@304 71dcc9de-d417-0410-9af5-da40c76e7ee4

neo/storage/operation.py

@@ -73,7 +73,7 @@ class OperationEventHandler(StorageEventHandler):
         if uuid is not None:
             app = self.app
             node = app.nm.getNodeByUUID(uuid)
-            if node.getNodeType() == CLIENT_NODE_TYPE:
+            if node is not None and node.getNodeType() == CLIENT_NODE_TYPE:
                 for tid, t in app.transaction_dict.items():
                     if t.getUUID() == uuid:
                         for o in t.getObjectList():