Cron Daemon munin error

I’ve started regularly getting an error from Cron Daemon:

Cron <munin@crabapple> if [ -x /usr/bin/munin-cron ]; then /usr/bin/munin-cron; fi

[FATAL] There is nothing to do here, since there are no nodes with any plugins.  Please refer to at /usr/share/munin/munin-html line 40.

When I navigate to /admin/munin/, Munin seems to be working fine.

If I run the following, it completes with no output.

su - munin --shell=/bin/bash

I tried adding --debug and spotted this warning a few times, but otherwise nothing noteworthy in the very verbose output.

2024/06/28 21:20:51 [WARNING] Missing configuration options for contact admin; skipping