https://en.wikipedia.org/wiki/User:Enterprisey/link-deleted-revs should be a core feature of MediaWiki.
Steps to reproduce: Click https://en.wikipedia.org/w/index.php?title=&oldid=844151270
Expected behavior: Show administrators a link to the deleted revision, or the deleted revision itself.
Current behavior: "The revision #844151270 of the page named "Main Page" does not exist."
Possibly related: T59445