private function badValue($varName, $typeName, $val, $line, $column, $errors = null)
 {
     $realErrors = !$errors ? ["Expected type \"{$typeName}\", found {$val}."] : $errors;
     return FormattedError::create(DefaultValuesOfCorrectType::badValueForDefaultArgMessage($varName, $typeName, $val, $realErrors), [new SourceLocation($line, $column)]);
 }