Installation error on Visioncart plugin

Attempting to preserve files at /core/components/visioncart into archive /core/packages/visioncart-0.7.0-rc5/modCategory/c716d9c19996467b951a7fdfa4041037.0.preserved.zip
Attempting to preserve files at /assets/components/visioncart into archive /core/packages/visioncart-0.7.0-rc5/modCategory/c716d9c19996467b951a7fdfa4041037.1.preserved.zip
[b]Could not load package metadata for package visioncart.[/b]

Fatal error: Call to a member function route() on a non-object in /core/cache/includes/elements/modplugin/28.include.cache.php on line 36

<?php
function elements_modplugin_28($scriptProperties= array()) {
global $modx;
if (is_array($scriptProperties)) {
extract($scriptProperties, EXTR_SKIP);
}
/**
 * @package visioncart
 */

if ($modx->context->get('key') == 'mgr') {
	switch((string) $modx->event->name) {
		case 'OnBeforeCacheUpdate':
			$modx->cacheManager->refresh(array(
				'visioncart' => array(
					'.php'
				)
			));
			break;
	}
	return false;
}

switch((string) $modx->event->name) {
	case 'OnWebPageInit':
		$corePath = $modx->getOption('visioncart.core_path', null, $modx->getOption('core_path', null, MODX_CORE_PATH));
		$modx->addPackage('visioncart', $corePath.'components/visioncart/model/');
		$modx->visioncart = $modx->getService('visioncart', 'VisionCart', $corePath.'components/visioncart/model/visioncart/', array(
			'method' => (string) (isset($_REQUEST['method']) && $_REQUEST['method'] != '') ? strtolower($_REQUEST['method']) : 'resource',
			'initialize' => 'plugin',
			'context' => (string) $modx->context->get('key'),
			'event' => (string) $modx->event->name
		));
		break;
	case 'OnPageNotFound':
		$modx->visioncart->route(array(
			'method' => (string) (isset($_REQUEST['method']) && $_REQUEST['method'] != '') ? strtolower($_REQUEST['method']) : 'resource',
			'initialize' => 'plugin',
			'context' => (string) $modx->context->get('key'),
			'event' => (string) $modx->event->name
		));
		break;

	case 'OnLoadWebDocument':
		$modx->visioncart->assign(array(
			'method' => (string) (isset($_REQUEST['method']) && $_REQUEST['method'] != '') ? strtolower($_REQUEST['method']) : 'resource',
			'initialize' => 'plugin',
			'context' => (string) $modx->context->get('key'),
			'event' => (string) $modx->event->name
		));
		break;
	default:
		//exit($modx->event->name);
		break;
}
}

switch((string) $modx->event->name) {
    case 'OnWebPageInit':
    case 'OnPageNotFound':
    case 'OnLoadWebDocument':
        $corePath = $modx->getOption('visioncart.core_path', null, $modx->getOption('core_path', null, MODX_CORE_PATH));
        if (! $modx->addPackage('visioncart', $corePath.'components/visioncart/model/')) {
            $modx->log(modX::LOG_LEVEL_ERROR, '[visioncart plugin] addPackage() failed');
        }
        $modx->visioncart = $modx->getService('visioncart', 'VisionCart', $corePath.'components/visioncart/model/visioncart/', array(
            'method' => (string) (isset($_REQUEST['method']) && $_REQUEST['method'] != '') ? strtolower($_REQUEST['method']) : 'resource',
            'initialize' => 'plugin',
            'context' => (string) $modx->context->get('key'),
            'event' => (string) $modx->event->name
        ));
        break;
   
    default:
        //exit($modx->event->name);
        break;
}