How to reproduce:

1. Start himitsud.
2. Trigger launch of grant prompter (e.g. with `hiq -d`).
3. Kill the propmter.

himitsud aborts after killing the prompter with following error:

Abort: .../himitsu/cmd/himitsud/cmd.ha:20:1: execution reached unreachable code (compiler bug)

That line is the match expression of himitsud::cmd::strerror().  The
code looks correct, the match expression is exhaustive.  There is a
chance this is a Hare bug, probably a variant of
https://todo.sr.ht/~sircmpwn/hare/730 (??).