function registerLanguage(languageName, languageDefinition) {
      let lang = null;
      try {
        lang = languageDefinition(hljs);
      } catch (error$1) {
        error("Language definition for '{}' could not be registered.".replace("{}", languageName));
        // hard or soft error
        if (!SAFE_MODE) { throw error$1; } else { error(error$1); }
        // languages that have serious errors are replaced with essentially a
        // "plaintext" stand-in so that the code blocks will still get normal
        // css classes applied to them - and one bad language won't break the
        // entire highlighter
        lang = PLAINTEXT_LANGUAGE;
      }
      // give it a temporary name if it doesn't have one in the meta-data
      if (!lang.name) lang.name = languageName;
      languages[languageName] = lang;
      lang.rawDefinition = languageDefinition.bind(null, hljs);

      if (lang.aliases) {
        registerAliases(lang.aliases, { languageName });
      }
    }
Register a language grammar module

@param {string} languageName
@param {LanguageFn} languageDefinition