Make a SongList.Current() return a copy of a current song.

internal/radio/song.go

@@ -76,7 +76,12 @@ func (sl *SongList) Current() *Song {
 	if sl.current.StartAt.Year() == 1 {
 		return nil
 	}
-	return &sl.current
+	return &Song{
+		Artist:       sl.current.Artist,
+		Title:        sl.current.Title,
+		Duration:     sl.current.Duration,
+		MaxListeners: sl.current.MaxListeners,
+		StartAt:      sl.current.StartAt}
 }
 
 // UpdateCurrentMaxListeners checks and updates a maximal number of listeners