Program: 47081
Project: 47081
Buggy source:
@Override public InputStream getThumbnailInputStream() throws IOException {
  if (useSuperThumb || getParent() instanceof FileTranscodeVirtualFolder && (getMediaSubtitle() != null || getMediaAudio() != null)) {
    return super.getThumbnailInputStream();
  }
  File file=getFile();
  File cachedThumbnail=null;
  if (getParent() != null && getParent() instanceof RealFile) {
    cachedThumbnail=((RealFile)getParent()).getPotentialCover();
  }
  File thumbFolder=null;
  boolean alternativeCheck=false;
  while (cachedThumbnail == null) {
    if (thumbFolder == null && getType() != Format.IMAGE) {
      thumbFolder=file.getParentFile();
    }
    cachedThumbnail=FileUtil.getFileNameWithNewExtension(thumbFolder,file,"String_Node_Str");
    if (cachedThumbnail == null) {
      cachedThumbnail=FileUtil.getFileNameWithNewExtension(thumbFolder,file,"String_Node_Str");
    }
    if (cachedThumbnail == null) {
      cachedThumbnail=FileUtil.getFileNameWithAddedExtension(thumbFolder,file,"String_Node_Str");
    }
    if (cachedThumbnail == null) {
      cachedThumbnail=FileUtil.getFileNameWithAddedExtension(thumbFolder,file,"String_Node_Str");
    }
    if (alternativeCheck) {
      break;
    }
    if (StringUtils.isNotBlank(configuration.getAlternateThumbFolder())) {
      thumbFolder=new File(configuration.getAlternateThumbFolder());
      if (!thumbFolder.isDirectory()) {
        thumbFolder=null;
        break;
      }
    }
    alternativeCheck=true;
  }
  if (file.isDirectory()) {
    cachedThumbnail=FileUtil.getFileNameWithNewExtension(file.getParentFile(),file,"String_Node_Str");
    if (cachedThumbnail == null) {
      cachedThumbnail=FileUtil.getFileNameWithNewExtension(file.getParentFile(),file,"String_Node_Str");
    }
  }
  boolean hasAlreadyEmbeddedCoverArt=getType() == Format.AUDIO && getMedia() != null && getMedia().getThumb() != null;
  if (cachedThumbnail != null && (!hasAlreadyEmbeddedCoverArt || file.isDirectory())) {
    return new FileInputStream(cachedThumbnail);
  }
 else   if (getMedia() != null && getMedia().getThumb() != null) {
    return getMedia().getThumbnailInputStream();
  }
 else {
    return super.getThumbnailInputStream();
  }
}

Fixed version (ground truth):
@Override public InputStream getThumbnailInputStream() throws IOException {
  if (useSuperThumb || getParent() instanceof FileTranscodeVirtualFolder && (getMediaSubtitle() != null || getMediaAudio() != null)) {
    return super.getThumbnailInputStream();
  }
  File file=getFile();
  File cachedThumbnail=null;
  File thumbFolder=null;
  boolean alternativeCheck=false;
  while (cachedThumbnail == null) {
    if (thumbFolder == null && getType() != Format.IMAGE) {
      thumbFolder=file.getParentFile();
    }
    cachedThumbnail=FileUtil.getFileNameWithNewExtension(thumbFolder,file,"String_Node_Str");
    if (cachedThumbnail != null) {
      break;
    }
    cachedThumbnail=FileUtil.getFileNameWithNewExtension(thumbFolder,file,"String_Node_Str");
    if (cachedThumbnail != null) {
      break;
    }
    cachedThumbnail=FileUtil.getFileNameWithAddedExtension(thumbFolder,file,"String_Node_Str");
    if (cachedThumbnail != null) {
      break;
    }
    cachedThumbnail=FileUtil.getFileNameWithAddedExtension(thumbFolder,file,"String_Node_Str");
    if (cachedThumbnail != null) {
      break;
    }
    if (getParent() != null && getParent() instanceof RealFile) {
      cachedThumbnail=((RealFile)getParent()).getPotentialCover();
    }
    if (cachedThumbnail != null || alternativeCheck) {
      break;
    }
    if (StringUtils.isNotBlank(configuration.getAlternateThumbFolder())) {
      thumbFolder=new File(configuration.getAlternateThumbFolder());
      if (!thumbFolder.isDirectory()) {
        thumbFolder=null;
        break;
      }
    }
    alternativeCheck=true;
  }
  if (file.isDirectory()) {
    cachedThumbnail=FileUtil.getFileNameWithNewExtension(file.getParentFile(),file,"String_Node_Str");
    if (cachedThumbnail == null) {
      cachedThumbnail=FileUtil.getFileNameWithNewExtension(file.getParentFile(),file,"String_Node_Str");
    }
  }
  boolean hasAlreadyEmbeddedCoverArt=getType() == Format.AUDIO && getMedia() != null && getMedia().getThumb() != null;
  if (cachedThumbnail != null && (!hasAlreadyEmbeddedCoverArt || file.isDirectory())) {
    return new FileInputStream(cachedThumbnail);
  }
 else   if (getMedia() != null && getMedia().getThumb() != null) {
    return getMedia().getThumbnailInputStream();
  }
 else {
    return super.getThumbnailInputStream();
  }
}