Properly construct File_keys when handling live errors requests
Properly construct File_keys when handling live errors requests

Summary: This is the same as the change made in D27577168 (https://github.com/facebook/flow/commit/a7e78a734dfa2b4c071ea92687eecf5f781fa448), but at a different callsite

Reviewed By: mroch

Differential Revision: D27596742

fbshipit-source-id: 01c794904f41f27c8a5d43a784dae2bdbb6bc1bf

mroch/flow,facebook/flow,mroch/flow,mroch/flow,facebook/flow,mroch/flow,mroch/flow,facebook/flow,facebook/flow,facebook/flow,mroch/flow,facebook/flow,facebook/flow,mroch/flow