Program: 36611
Project: 36611
Buggy source:
@Override public void init(){
  volume.setMin(PLAYBACK.getVolumeMin());
  volume.setMax(PLAYBACK.getVolumeMax());
  volume.setValue(PLAYBACK.getVolume());
  volume.valueProperty().bindBidirectional(PLAYBACK.volumeProperty());
  seeker.bindTime(PLAYBACK.totalTimeProperty(),PLAYBACK.currentTimeProperty());
  seeker.setChapterSnapDistance(GUI.snapDistance);
  seekerPane.setCenter(seeker);
  prevB=new Icon(STEP_BACKWARD,14,null,PlaylistManager::playPreviousItem);
  playB=new Icon(null,14,null,PLAYBACK::pause_resume);
  stopB=new Icon(STOP,14,null,PLAYBACK::stop);
  nextB=new Icon(STEP_FORWARD,14,null,PlaylistManager::playNextItem);
  controlBox.getChildren().addAll(prevB,playB,stopB,nextB);
  volB=new Icon(null,14,null,PLAYBACK::toggleMute);
  volBox.getChildren().add(0,volB);
  d1=maintain(PLAYBACK.volumeProperty(),v -> muteChanged(PLAYBACK.isMute(),v.doubleValue()));
  d2=maintain(PLAYBACK.muteProperty(),m -> muteChanged(m,PLAYBACK.getVolume()));
  d3=maintain(PLAYBACK.statusProperty(),this::statusChanged);
  d4=Player.playingtem.subscribeToUpdates(this::playbackItemChanged);
  playbackItemChanged(Player.playingtem.get());
  d5=maintain(PLAYBACK.currentTimeProperty(),t -> currentTimeChanged());
  root.setOnDragOver(DragUtil.audioDragAccepthandler);
  root.setOnDragDropped(e -> {
    if (DragUtil.hasAudio(e.getDragboard())) {
      List<Item> items=DragUtil.getAudioItems(e);
      e.setDropCompleted(true);
      e.consume();
      if (playDropped) {
        PlaylistManager.playPlaylist(new Playlist(items.stream().map(Item::getURI),true));
      }
 else {
        PlaylistManager.addItems(items);
      }
    }
  }
);
}

Fixed version (ground truth):
@Override public void init(){
  volume.setMin(PLAYBACK.getVolumeMin());
  volume.setMax(PLAYBACK.getVolumeMax());
  volume.setValue(PLAYBACK.getVolume());
  volume.valueProperty().bindBidirectional(PLAYBACK.volumeProperty());
  seeker.bindTime(PLAYBACK.totalTimeProperty(),PLAYBACK.currentTimeProperty());
  d6=maintain(GUI.snapDistance,d -> d,seeker.chapterSnapDistance);
  seekerPane.setCenter(seeker);
  prevB=new Icon(STEP_BACKWARD,14,null,PlaylistManager::playPreviousItem);
  playB=new Icon(null,14,null,PLAYBACK::pause_resume);
  stopB=new Icon(STOP,14,null,PLAYBACK::stop);
  nextB=new Icon(STEP_FORWARD,14,null,PlaylistManager::playNextItem);
  controlBox.getChildren().addAll(prevB,playB,stopB,nextB);
  volB=new Icon(null,14,null,PLAYBACK::toggleMute);
  volBox.getChildren().add(0,volB);
  d1=maintain(PLAYBACK.volumeProperty(),v -> muteChanged(PLAYBACK.isMute(),v.doubleValue()));
  d2=maintain(PLAYBACK.muteProperty(),m -> muteChanged(m,PLAYBACK.getVolume()));
  d3=maintain(PLAYBACK.statusProperty(),this::statusChanged);
  d4=Player.playingtem.subscribeToUpdates(this::playbackItemChanged);
  playbackItemChanged(Player.playingtem.get());
  d5=maintain(PLAYBACK.currentTimeProperty(),t -> currentTimeChanged());
  root.setOnDragOver(DragUtil.audioDragAccepthandler);
  root.setOnDragDropped(e -> {
    if (DragUtil.hasAudio(e.getDragboard())) {
      List<Item> items=DragUtil.getAudioItems(e);
      e.setDropCompleted(true);
      e.consume();
      if (playDropped) {
        PlaylistManager.playPlaylist(new Playlist(items.stream().map(Item::getURI),true));
      }
 else {
        PlaylistManager.addItems(items);
      }
    }
  }
);
  ds=asList(d1,d2,d3,d4,d5,d6);
}