Program: 178450
Project: 178450
Buggy source:
private TreeOperation handleBackspaceOrDeleteKeyOnEmptyTexts(boolean isBackspace,Node node,Node rightParagraph,Node leftParagraph){
  org.xwiki.gwt.dom.client.Document document=getTextArea().getDocument();
  Range range=document.createRange();
  if (isBackspace) {
    range.setStartAfter(document.getBody().getFirstChild());
    range.setEndBefore(node);
  }
 else {
    range.setStartAfter(node);
    range.setEndBefore(document.getBody().getLastChild());
  }
  TreeOperation op=null;
  List<Text> nonEmptyTextNodes=getNonEmptyTextNodes(range);
  if (nonEmptyTextNodes.size() > 0) {
    int idx=isBackspace ? nonEmptyTextNodes.size() - 1 : 0;
    Node prevNonEmptyTextNode=nonEmptyTextNodes.get(idx);
    log.fine("String_Node_Str" + prevNonEmptyTextNode.getNodeValue());
    List<Integer> path;
    if (node.getParentNode() == prevNonEmptyTextNode.getParentNode()) {
      int deletePos=isBackspace ? prevNonEmptyTextNode.getNodeValue().length() - 1 : 0;
      path=TreeHelper.getLocator(prevNonEmptyTextNode);
      op=new TreeDeleteText(clientJupiter.getSiteId(),deletePos,TreeHelper.toIntArray(path));
    }
 else {
      int lBbrCount=Element.as(leftParagraph).getElementsByTagName(BR).getLength();
      int rBbrCount=Element.as(rightParagraph).getElementsByTagName(BR).getLength();
      path=TreeHelper.getLocator(prevNonEmptyTextNode);
      op=new TreeMergeParagraph(clientJupiter.getSiteId(),path.get(0),leftParagraph.getChildCount() - lBbrCount,rightParagraph.getChildCount() - rBbrCount);
      op.setPath(TreeHelper.toIntArray(path));
    }
  }
  return op;
}

Fixed version (ground truth):
private TreeOperation handleBackspaceOrDeleteKeyOnEmptyTexts(boolean isBackspace,Node node,List<Integer> path,Node rightParagraph,Node leftParagraph){
  org.xwiki.gwt.dom.client.Document document=getTextArea().getDocument();
  Range range=document.createRange();
  if (isBackspace) {
    range.setStart(document.getBody().getFirstChild(),0);
    range.setEndBefore(node);
  }
 else {
    range.setStartAfter(node);
    range.setEndBefore(document.getBody().getLastChild());
  }
  TreeOperation op=null;
  List<Text> nonEmptyTextNodes=getNonEmptyTextNodes(range);
  if (nonEmptyTextNodes.size() > 0) {
    int idx=isBackspace ? nonEmptyTextNodes.size() - 1 : 0;
    Node prevNonEmptyTextNode=nonEmptyTextNodes.get(idx);
    log.fine("String_Node_Str" + prevNonEmptyTextNode.getNodeValue());
    if (node.getParentNode() == prevNonEmptyTextNode.getParentNode()) {
      int deletePos=isBackspace ? prevNonEmptyTextNode.getNodeValue().length() - 1 : 0;
      op=new TreeDeleteText(clientJupiter.getSiteId(),deletePos,TreeHelper.toIntArray(path));
    }
 else {
      if ((isBackspace && leftParagraph != null) || (!isBackspace && rightParagraph != null)) {
        int lBbrCount=Element.as(leftParagraph).getElementsByTagName(BR).getLength();
        int rBbrCount=Element.as(rightParagraph).getElementsByTagName(BR).getLength();
        op=new TreeMergeParagraph(clientJupiter.getSiteId(),path.get(0),leftParagraph.getChildCount() - lBbrCount,rightParagraph.getChildCount() - rBbrCount);
        op.setPath(TreeHelper.toIntArray(path));
      }
    }
  }
  return op;
}