Характеристики товаров и язык - Общие вопросы и ошибки

$list_productfields = $_productfields->getList(1);

$lang = $app->getLanguage();
$defLang = $lang->getTag();
$curLang = 'ru-RU';
$lang->setLanguage($curLang);

Error: Could not find template "isis".: Call to a member function getTag() on nulls

Call to a member function getTag() on null			<br/>/var/www/import.localhost/public_html/administrator/components/com_jshopping/importexport/ws_xml_import/cli.php:56

$app = JFactory::getApplication();
$lang = $app->getLanguage();
echo '<pre>'.print_r($lang,1).'</pre>';
$lang->setLanguage('ru-RU');

$app = JFactory::getApplication('administrator');
		$lang= new \Joomla\CMS\Language\Language('ru-RU');
		$lang->setDefault('ru-RU');
		JFactory::getLanguage()->setDefault('ru-RU');
		print_r(JFactory::getLanguage()); die();

$lang->setLanguage('ru-RU');

		$app = JFactory::getApplication('administrator',['language'=>'ru-RU']); //Вот только плевать на переданные параметры!!
			// Build our language object
		$lang = \JLanguage::getInstance('ru-RU');

		// Load the language to the API
		$app->loadLanguage($lang);

		// Register the language object with \JFactory
		\JFactory::$language = $app->getLanguage();

		// Load the library language files
		$app->getLanguage()->load('lib_joomla', JPATH_ADMINISTRATOR);