vitest sometimes freezes

[KonradHoeffner]

npm run test, which calls vitest run, sometimes hangs.
Probably related to vitest-dev/vitest#2008.
vitest-dev/vitest#2008 (comment) remarks that circular dependencies caused this problem in one case and removing them fixed the issue. Probably a good idea to get rid of as many of them as possible but it is hard to do and takes a while, track in #406.

vitest-dev/vitest#2008 (comment) got rid of the freezes by using the --no-threads option, so we should try that as well.