#vulnerable code 
                              @Override void promoteNameToValue() throws IOException {
    Map.Entry<?, ?> peeked = require(Map.Entry.class, Token.NAME);

    push(peeked.getKey());
    stack[stackSize - 2] = peeked.getValue();
  } 
                            #location 4 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                              @Override void promoteNameToValue() throws IOException {
    if (hasNext()) {
      String name = nextName();
      push(name);
    }
  }