message: Properly handle the string "NULL" in a comparison
diff: @@ -499,11 +499,15 @@ bool compare_values(MaterializedQueryResult &result, Value &lvalue, string rvalu
  auto sql_type = result.sql_types[current_column];
  try {
  if (rvalue_str == "NULL") {
  + if (sql_type.id != SQLTypeId::VARCHAR && lvalue.str_value != "NULL") {
  rvalue = Value(GetInternalType(sql_type));
  rvalue.is_null = true;
  } else {
  rvalue = Value(rvalue_str).CastAs(SQLType::VARCHAR, sql_type);
  }
  + } else {
  + rvalue = Value(rvalue_str).CastAs(SQLType::VARCHAR, sql_type);
  + }
  } catch(std::exception &ex) {
  print_error_header("Test error!", zScriptFile, query_line);
  print_line_sep();
  