assignParserForLanguage = (options = {}) => {
  const { parserForLanguage: parserForLanguageOption, ...rest } = options;
  /** @type {ParserForLanguage} */
  const parserForLanguage = freeze(
    assign(create(null), defaultParserForLanguage, parserForLanguageOption),
  );
  return { ...rest, parserForLanguage };
}
Add the default parserForLanguage option.
@param {Options} [options]
@returns {Options}