Unknown Existential Variable mysterious error message

[rlmark]

This is probably a pretty unlikely corner case for others to hit but it's a bit of a puzzle. If you try to do a doc link ''{{doc doc [doc]({a link to a doc})'' and that doc term happens to be called run 😬 you'll get an error about

UnknownExistentialVariable:
unsolved

unknownExistentialVariable.md

[kanwren]

This doesn't seem to be specific to docs. For example, the following works fine:

run : ()
run = ()

foo : ()
foo = run

but when run is not found like this:

foo : ()
foo = run

it will fail (as it should) but with the above unhelpful error message.