エラー

An exception has been thrown during the rendering of a template ("Plugin\PluginName\Event::__construct(): Argument #1 ($twig) must be of type Twig_Environment, Twig\Environment given, called in /home/www/eccube-root/var/cache/dev/Container8nl8xnu/getEventService.php on line 29").

原因コード

root/app/Plugin/PluginName/Event.php

<?php

namespace Plugin\PluginName;

use Symfony\Component\EventDispatcher\EventSubscriberInterface;
use Eccube\Event\TemplateEvent;

/**
* ページをプラグイン用に差し替え
*/

class Event implements EventSubscriberInterface
{
    public function __construct(\Twig_Environment $twig)
    {
        $this->twig = $twig;
    }
    
    /**
     * @return array
     */
    public static function getSubscribedEvents()
    {
        return [
            'Cart/index.twig' => ['onTemplateCartIndex', 999999]
        ];
    }
    
    public function onTemplateCartIndex(TemplateEvent $event)
    {
        $source = $this->twig->getLoader()
            ->getSourceContext("@PluginName/default/Cart/index.twig")
            ->getCode();
                
        $event->setSource($source);
    }
}

14行目
\Twig_Environment
を
\Twig\Environment
で上書き

エラー解消