Error
MediaWiki version: 1.35.0-wmf.39
While deploying a config change https://gerrit.wikimedia.org/r/c/operations/mediawiki-config/+/569259
which was then reverted https://gerrit.wikimedia.org/r/c/operations/mediawiki-config/+/608838
https://gerrit.wikimedia.org/r/c/operations/mediawiki-config/+/608839 is the replacement
as part of T254315
Only happened on commonswiki
Call to a member function getSourceName() on null