A quick check shows that this is not used anywhere else in the codebase.
$ ag unimplemented
backend/player/dlna/dlnaplayer.go
34:var unimplemented = errors.New("unimplemented")
Remove doSetNewTrackOrder from ui/browsing/nowplayingpage.go: it seems
there is a same named method that is used elsewhere, instead of the one
we are removing.
$ ag doSetNewTrackOrder
ui/browsing/playlistpage.go
95: a.tracklist.OnReorderTracks = a.doSetNewTrackOrder
210:func (a *PlaylistPage) doSetNewTrackOrder(ids []string, newPos int) {
ui/browsing/nowplayingpage.go
509:func (a *NowPlayingPage) doSetNewTrackOrder(idxs []int, insertPos int) {