message: fix(Util): isSimpleLiteral not robust
diff: @@ -447,7 +447,9 @@ EvalMultitypeValue
  return ret_femv;
  }
  - if (this->isSimpleLiteral() && x.isSimpleLiteral())
  + // TODO: isSimpleLiteral seems not robust
  + // if (this->isSimpleLiteral() && x.isSimpleLiteral())
  + if (this->datatype == literal && x.datatype == literal)
  {
  ret_femv.bool_value = (this->str_value < x.str_value);
  