Summary: If unsub fails, the error doesn't get propagated out, instead a nil error gets passed out which then causes a nil pointer error.

Test Plan: Tests don't break, still need to see what causes the underlying bug that gave us some issues.

Reviewers: vihang, michelle

Reviewed By: vihang, michelle

Differential Revision: https://phab.corp.pixielabs.ai/D9362

GitOrigin-RevId: 60b9d85b84a3e7d25cd87e8e1083f7e0550fe656