R1:3fc807bed162

Fix exception for new error stuff in Conduit

Summary: This might be `null`.

Test Plan: Loaded, got exception, applied patch, no exception. Viewed a method with an actual message too, that also worked.

Reviewers: chad, btrahan

Reviewed By: chad

CC: aran

Differential Revision: https://secure.phabricator.com/D7955