This has to do with the newly introduced async-worker API. If I panic inside a worker subscriber I get the error:
[FATAL] [1749692769.253571881] [rclrs.basic_executor]: WaitSetRunner unexpectedly dropped. This should never happen. Please report this to the rclrs maintainers with a minimal reproducible example.
It's a bit weird because the entire node does not die but just sits there.
I'll post a minimal reproducible example in a bit.