Do not panic if when updatePlaylist is called with a non-existent ID.

Fix #2876

core/playlists.go

@@ -231,13 +231,17 @@ func (s *playlists) Update(ctx context.Context, playlistID string,
 		var pls *model.Playlist
 		var err error
 		repo := tx.Playlist(ctx)
+		tracks := repo.Tracks(playlistID, true)
+		if tracks == nil {
+			return fmt.Errorf("%w: playlist '%s'", model.ErrNotFound, playlistID)
+		}
 		if needsTrackRefresh {
 			pls, err = repo.GetWithTracks(playlistID, true)
 			pls.RemoveTracks(idxToRemove)
 			pls.AddTracks(idsToAdd)
 		} else {
 			if len(idsToAdd) > 0 {
-				_, err = repo.Tracks(playlistID, true).Add(idsToAdd)
+				_, err = tracks.Add(idsToAdd)
 				if err != nil {
 					return err
 				}
@@ -264,7 +268,7 @@ func (s *playlists) Update(ctx context.Context, playlistID string,
 		}
 		// Special case: The playlist is now empty
 		if len(idxToRemove) > 0 && len(pls.Tracks) == 0 {
-			if err = repo.Tracks(playlistID, true).DeleteAll(); err != nil {
+			if err = tracks.DeleteAll(); err != nil {
 				return err
 			}
 		}

persistence/playlist_track_repository.go

@@ -40,7 +40,7 @@ func (r *playlistRepository) Tracks(playlistId string, refreshSmartPlaylist bool
 
 	pls, err := r.Get(playlistId)
 	if err != nil {
-		log.Error(r.ctx, "Error getting playlist's tracks - THIS SHOULD NOT HAPPEN!", "playlistId", playlistId, err)
+		log.Warn(r.ctx, "Error getting playlist's tracks", "playlistId", playlistId, err)
 		return nil
 	}
 	if refreshSmartPlaylist {

server/subsonic/playlists.go

@@ -43,7 +43,7 @@ func (api *Router) getPlaylist(ctx context.Context, id string) (*responses.Subso
 	pls, err := api.ds.Playlist(ctx).GetWithTracks(id, true)
 	if errors.Is(err, model.ErrNotFound) {
 		log.Error(ctx, err.Error(), "id", id)
-		return nil, newError(responses.ErrorDataNotFound, "Directory not found")
+		return nil, newError(responses.ErrorDataNotFound, "playlist not found")
 	}
 	if err != nil {
 		log.Error(ctx, err)
@@ -150,7 +150,7 @@ func (api *Router) UpdatePlaylist(r *http.Request) (*responses.Subsonic, error)
 		return nil, newError(responses.ErrorAuthorizationFail)
 	}
 	if err != nil {
-		log.Error(r, err)
+		log.Error(r, "Error updating playlist", "id", playlistId, err)
 		return nil, err
 	}
 	return newResponse(), nil