And one more thing.
What if this `die` will actually happen? guardian will exit and daemon will keep working, right?
It'll probably fail soon too because it's stdout will be broken; and it'll probably be garbage-collected by watchdog because `check_daemon` checks both for guardian and for daemon's pids.
But still, I think we should be more careful and wrap everything that can fail in some kind of eval and handle errors.
I.e., call `$kill_sub` before failing.