Не могу обновить превью ms2Gallery

<?php
define('MODX_API_MODE', true);
require 'index.php';

$modx->getService('error','error.modError');
$modx->setLogLevel(modX::LOG_LEVEL_ERROR);
$modx->setLogTarget(XPDO_CLI_MODE ? 'ECHO' : 'HTML');

$modx->addPackage('ms2gallery', MODX_CORE_PATH . 'components/ms2gallery/model/');
$files = $modx->getIterator('msResourceFile', array('parent' => 0));
foreach ($files as $file) {
	$children = $file->getMany('Children');
	foreach ($children as $child) {
		$child->remove();
	}
	$file->generateThumbnails();
}

echo microtime(true) - $modx->startTime;

PHP Fatal error:  Call to a member function removeObject() on a non-object in /home/admin/web/new.partyinthehouse.ru/public_html/core/components/ms2gallery/model/ms2gallery/msresourcefile.class.php on line 219