fix potention spec panic

server/ctrlsubsonic/spec/construct_by_folder.go

@@ -34,7 +34,6 @@ func NewTCAlbumByFolder(f *model.Album) *TrackChild {
 func NewTCTrackByFolder(t *model.Track, parent *model.Album) *TrackChild {
 	trCh := &TrackChild{
 		ID:          t.ID,
-		Album:       t.Album.RightPath,
 		ContentType: t.MIME(),
 		Suffix:      t.Ext(),
 		Size:        t.Size,
@@ -57,6 +56,9 @@ func NewTCTrackByFolder(t *model.Track, parent *model.Album) *TrackChild {
 	if parent.Cover != "" {
 		trCh.CoverID = parent.ID
 	}
+	if t.Album != nil {
+		trCh.Album = t.Album.RightPath
+	}
 	return trCh
 }
 

server/ctrlsubsonic/spec/construct_by_tags.go

@@ -41,7 +41,6 @@ func NewTrackByTags(t *model.Track, album *model.Album) *TrackChild {
 		),
 		Album:    album.TagTitle,
 		AlbumID:  album.ID,
-		ArtistID: album.TagArtist.ID,
 		Duration: t.Length,
 		Bitrate:  t.Bitrate,
 		Type:     "music",
@@ -49,6 +48,9 @@ func NewTrackByTags(t *model.Track, album *model.Album) *TrackChild {
 	if album.Cover != "" {
 		ret.CoverID = album.ID
 	}
+	if album.TagArtist != nil {
+		ret.ArtistID = album.TagArtist.ID
+	}
 	return ret
 }