Previous versions of MPD would call SetVolume on enabled outputs before
they are ready, causing all of MPD to crash. Checking the really_enabled
flag prevents this, though it also prevents setting volume before the
player starts.
Before (with the PipeWire output):
[i] ~$ mpc clear
volume: 81% repeat: off random: off single: off consume: off
[i] ~$ systemctl --user restart mpd.service
[i] ~$ mpc volume 100
MPD error: Connection closed by the server
[i] ~ 1 $
After:
[i] ~$ # mpd is freshly started w/o anything in the queue
[i] ~$ mpc
volume:100% repeat: off random: off single: off consume: off
[i] ~$ mpc volume 80
MPD error: problems setting volume
[i] ~ 1 $ mpc
volume:100% repeat: off random: off single: off consume: off
[i] ~$
35dbc1a90c