Fix null pointer dereference in thrift python binding
Fix null pointer dereference in thrift python binding

Differential Revision: D30061019

fbshipit-source-id: ab70423f55e22387d295fc3f1de225de7f905efa

facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift