all playlist functionality works now

backend/mediaprovider/mediaprovider.go

@@ -66,11 +66,6 @@ type Server interface {
 	MediaProvider() MediaProvider
 }
 
-type IDAndIndex struct {
-	ID    string
-	Index int
-}
-
 type MediaProvider interface {
 	SetPrefetchCoverCallback(cb func(coverArtID string))
 
@@ -124,9 +119,7 @@ type MediaProvider interface {
 
 	AddPlaylistTracks(id string, trackIDsToAdd []string) error
 
-	// Some MediaProviders use ids and others indexes for removing tracks,
-	// so need to supply both.
-	RemovePlaylistTracks(id string, trackRemoveInfo []IDAndIndex) error
+	RemovePlaylistTracks(id string, trackIdxsToRemove []int) error
 
 	ReplacePlaylistTracks(id string, trackIDs []string) error