Steps to Reproduce:
- Log in as an admin on enwiki
- Navigate to https://en.wikipedia.org/wiki/Special:Undelete/User:RoySmith/sandbox/del-test
- Click any of the active diff links in the "Page history" section
Alternatively, skip the last two steps and go directly to:
You get to a page which says:
[XcbNGQpAICAAAJ8dNJcAAACO] 2019-11-09 14:28:41: Fatal exception of type "InvalidArgumentException"
Not an internal error.