getLanguageName = languageCode => {
  if (!languageCode || languageCode.length < 2) {
    return null
  }

  let language = ''

  // First try to get an exact language via 4-letter ISO code.
  if (languageCode.length === 5) {
    language = getHunspellLanguageName(languageCode)
    if (language) {
      return language
    }
  }

  language = langMap.getNativeName(languageCode.substr(0, 2))
  if (language) {
    // Add language code to distinguish between native name (en-US, en-GB, ...).
    return `${language} (${languageCode})`
  }
  return `Unknown (${languageCode})`
}
Return the native language name by language code.

@param {string} langCode The ISO two or four-letter language code (e.g. en, en-US) or BCP-47 code.