Noticed by users (at a low volume, I think) after last week's deploy of T324149: Build a widget to display GitLab changes on related Phabricator tasks.
See T332234#8708974:
It says "Undefined index: state" in an unhandled exception, maybe triggered by the recent upgrade (and revert?).
I think I just failed to account for some empty response case from the GitLab API, or maybe a variant form of the data. Digging.