#vulnerable code 
                                @Override
    public void queueVariable(int level, Var var) {

	Integer iVal = varXToIndex.get(var);
	if (iVal == null)
	    iVal = varYToIndex.get(var);
	int i = iVal.intValue();

	indexQueue.add(i);

    } 
                            #location 7 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                @Override
    public void queueVariable(int level, Var var) {

	ArrayList<Integer> iValX = varXToIndex.get(var);
	ArrayList<Integer> iValY = varYToIndex.get(var);

	if (iValX != null)
	    for (int i : iValX)
		indexQueue.add(i);
	if (iValY != null)
	    for (int i : iValY)
		indexQueue.add(i);
	
    }