anchor.diff:  
   IconButton _nextButton(Color color) => IconButton(
         icon: Icon(Icons.skip_next),
  -      onPressed: getIt<AudioPlayer>().seekToNext,
  +      onPressed: getIt<AudioPlayer>().hasNext ? getIt<AudioPlayer>().seekToNext : null,
         iconSize: 24.0,
         color: color,
       );
  
positive.code: 
  IconButton _previousButton(Color color) => IconButton(
        icon: Icon(Icons.skip_previous),
        onPressed: getIt<AudioPlayer>().seekToPrevious,
        iconSize: 24.0,
        color: color,
      );
  
negative.code:         return Row(
            mainAxisAlignment: MainAxisAlignment.center,
            children: [
              _previousButton(foregroundColor),
              if (playing) _pauseButton(foregroundColor) else _playButton(foregroundColor),
              _nextButton(foregroundColor),
            ],
          );
        },
  