Shopware 6创建店面控制器失败：Call to a member function hasScope() on array

我按照官方文档/教程的代码创建了一个简单的Shopware 6控制器，但运行时始终报错：

Call to a member function hasScope() on array

附带堆栈追踪截图。以下是我的控制器代码、service.xml配置及路由配置，恳请协助排查问题：

控制器代码 #

<?php declare(strict_types=1);

namespace ArvKalbacherCustomization\Storefront\Controller;

use Shopware\Storefront\Controller\StorefrontController;
use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\Routing\Annotation\Route;

/**
 * @Route(defaults={"_routeScope"={"storefront"}})
 */
class ExampleController extends StorefrontController
{
    /**
     * @Route("/example", name="frontend.example.example", methods={"GET"})
     */
    public function showExample(): Response
    {
        return $this->renderStorefront('@ArvKalbacherCustomization/storefront/page/example.html.twig', [
            'example' => 'Hello world'
        ]);
    }
}

service.xml配置 #

<service id="ArvKalbacherCustomization\Storefront\Controller\ExampleController" public="true">
    <call method="setContainer">
        <argument type="service" id="service_container"/>
    </call>
</service>

路由配置 #

<?xml version="1.0" encoding="UTF-8" ?>
<routes xmlns="http://symfony.com/schema/routing"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:schemaLocation="http://symfony.com/schema/routing
        https://symfony.com/schema/routing/routing-1.0.xsd">

    <import resource="../../Storefront/Controller/**/*Controller.php" type="annotation"/>
</routes>

内容的提问来源于stack exchange，提问作者Aaron Sommer