If I install WikibaseQualityConstraints and WikibaseMediaInfo, the File page can contain Wikibase entity data even though the File page isn't an entity namespace.
The onBeforePageDisplay hook only adds the constraints js modules to pages in entity namespaces, so even though we need the js on the File page it isn't included
Change 572218 had a related patch set uploaded (by Cparle; owner: Cparle):
[mediawiki/extensions/WikibaseQualityConstraints@master] Add constraints js to pages contain entities (including within slots)
Change 572218 merged by jenkins-bot:
[mediawiki/extensions/WikibaseQualityConstraints@master] Add constraints js to pages contain entities (including within slots)
Wait… I’m rather late with this realization, but do you want those JS modules to be loaded on MediaInfo pages? I’m pretty sure they won’t work with the MediaInfo UI.
Hah yeah, I've since realised that they don't work with our UI, nor should they. Raised T245264 which is related