Program: 178439
Project: 178439
Buggy source:
public TreeOperation handleDeleteOnTextNode(Range caret){
  int pos=caret.getStartOffset();
  Node startContainer=caret.getStartContainer();
  Text textNode=Text.as(startContainer);
  List<Integer> path=TreeHelper.getLocator(startContainer);
  TreeOperation op=null;
  Element leftParagraph;
  Element rightParagraph;
  final Node ancestorBelowParagraph=getAncestorBelowParagraph(startContainer);
  leftParagraph=ancestorBelowParagraph.getParentElement();
  rightParagraph=leftParagraph.getNextSiblingElement();
  boolean isMerge=false;
  if (textNode != ancestorBelowParagraph) {
    isMerge=ancestorBelowParagraph == ancestorBelowParagraph.getParentNode().getLastChild();
    isMerge=isMerge && textNode == ancestorBelowParagraph.getLastChild();
  }
 else {
    isMerge=textNode == ancestorBelowParagraph.getParentElement().getLastChild();
  }
  isMerge=isMerge && ((rightParagraph != null) && (!rightParagraph.getClassName().toLowerCase().contains("String_Node_Str")));
  if (textNode.getLength() == pos) {
    if (isMerge) {
      int lBrCount=leftParagraph.getElementsByTagName(BR).getLength();
      int rBrCount=rightParagraph.getElementsByTagName(BR).getLength();
      op=new TreeMergeParagraph(clientJupiter.getSiteId(),path.get(0) + 1,leftParagraph.getChildCount() - lBrCount,rightParagraph.getChildCount() - rBrCount);
      op.setPath(TreeHelper.toIntArray(path));
    }
 else {
      log.fine("String_Node_Str");
    }
  }
 else {
    op=skipDeleteOnEmptyTexts(textNode,leftParagraph,rightParagraph);
  }
  return op;
}

Fixed version (ground truth):
public TreeOperation handleDeleteOnTextNode(Range caret){
  int pos=caret.getStartOffset();
  Node startContainer=caret.getStartContainer();
  Text textNode=Text.as(startContainer);
  List<Integer> path=TreeHelper.getLocator(startContainer);
  TreeOperation op=null;
  Element leftParagraph;
  Element rightParagraph;
  final Node ancestorBelowParagraph=getAncestorBelowParagraph(startContainer);
  leftParagraph=ancestorBelowParagraph.getParentElement();
  rightParagraph=leftParagraph.getNextSiblingElement();
  boolean isMerge=false;
  if (textNode != ancestorBelowParagraph) {
    isMerge=ancestorBelowParagraph == ancestorBelowParagraph.getParentNode().getLastChild();
    isMerge=isMerge && textNode == ancestorBelowParagraph.getLastChild();
  }
 else {
    isMerge=textNode == ancestorBelowParagraph.getParentElement().getLastChild();
  }
  isMerge=isMerge && ((rightParagraph != null) && (!rightParagraph.getClassName().toLowerCase().contains("String_Node_Str")));
  if (textNode.getLength() > 0) {
    if (textNode.getLength() == pos) {
      if (isMerge) {
        int lBrCount=leftParagraph.getElementsByTagName(BR).getLength();
        int rBrCount=rightParagraph.getElementsByTagName(BR).getLength();
        op=new TreeMergeParagraph(clientJupiter.getSiteId(),path.get(0) + 1,leftParagraph.getChildCount() - lBrCount,rightParagraph.getChildCount() - rBrCount);
        op.setPath(TreeHelper.toIntArray(path));
      }
 else {
        log.fine("String_Node_Str");
      }
    }
 else {
      op=new TreeDeleteText(clientJupiter.getSiteId(),pos,TreeHelper.toIntArray(path));
    }
  }
 else {
    op=skipDeleteOnEmptyTexts(textNode,leftParagraph,rightParagraph);
  }
  return op;
}