Knot 2.5.3 crash at shutdown

I have a test server running Knot 2.5.3. I started it up, with a few slave zones. I have these 2 options in the config:

journal-db-mode: asynchronous
zonefile-sync: 1h

I noticed that the journal was using up a lot of disk space (20GB, the default), so I added:

max-journal-db-size: 10G

to the config, and restarted the server. However, as it was shutting down, it crashed. In the log file, I see:

2017-07-17T13:04:15 info: stopping server
2017-07-17T13:04:15 info: updating persistent timer DB

However, the final "shutting down" message is missing. Instead, the system log shows several entries, showing a crash. Since those are many lines, I've attached them separately to this bug report instead of reporting it inline.knot-crash.log