coreshop/CoreShop

Hi,
followed docs for adding custom checkout step:
https://docs.coreshop.org/2.2.0/Development/Checkout/Checkout_Manager.html
using coreshop 3 beta-1

copied shipment step from core as own step, as first try.
file config/config.yaml:

core_shop_core:
    checkout:
        default:
            steps:
                shipment: false
                payment: false          # disables the payment step

                custom:
                    step: app.coreshop.checkout.custom
                    priority: 30

file bundles/FrontendBundle/Resources/config/services.yml:

    FrontendBundle\CoreShop\Checkout\Step\PackagingShippingCheckoutStep:
        public: true
        arguments:
            - '@CoreShop\Component\Shipping\Validator\ShippableCarrierValidatorInterface'
            - '@form.factory'
            - '@CoreShop\Component\Order\Manager\CartManagerInterface'

    app.coreshop.checkout.custom:
        alias: FrontendBundle\CoreShop\Checkout\Step\PackagingShippingCheckoutStep

file bundles/FrontendBundle/CoreShop/Checkout/Step/PackagingShippingCheckoutStep.php
```
<?php

declare(strict_types=1);

namespace FrontendBundle\CoreShop\Checkout\Step;

use CoreShop\Bundle\CoreBundle\Form\Type\Checkout\CarrierType;
use CoreShop\Component\Address\Model\AddressInterface;
use CoreShop\Component\Core\Model\CarrierInterface;
use CoreShop\Component\Order\Checkout\CheckoutException;
use CoreShop\Component\Order\Checkout\CheckoutStepInterface;
use CoreShop\Component\Order\Checkout\OptionalCheckoutStepInterface;
use CoreShop\Component\Order\Checkout\ValidationCheckoutStepInterface;
use CoreShop\Component\Order\Manager\CartManagerInterface;
use CoreShop\Component\Order\Model\OrderInterface;
use CoreShop\Component\Shipping\Validator\ShippableCarrierValidatorInterface;
use Symfony\Component\Form\FormFactoryInterface;
use Symfony\Component\Form\FormInterface;
use Symfony\Component\HttpFoundation\Request;
use Webmozart\Assert\Assert;

class PackagingShippingCheckoutStep implements CheckoutStepInterface, OptionalCheckoutStepInterface, ValidationCheckoutStepInterface
{
public function __construct(
private ShippableCarrierValidatorInterface $shippableCarrierValidator,
private FormFactoryInterface $formFactory,
private CartManagerInterface $cartManager)
{
}

public function getIdentifier(): string
{
    return 'pack_shipping';
}

public function isRequired(OrderInterface $cart): bool
{
    Assert::isInstanceOf($cart, \CoreShop\Component\Core\Model\OrderInterface::class);

    return $cart->hasShippableItems();
}

public function doAutoForward(OrderInterface $cart): bool
{
    Assert::isInstanceOf($cart, \CoreShop\Component\Core\Model\OrderInterface::class);

    return $cart->hasShippableItems() === false;
}

public function validate(OrderInterface $cart): bool
{
    Assert::isInstanceOf($cart, \CoreShop\Component\Core\Model\OrderInterface::class);

    return $cart->hasShippableItems() === false
        || ($cart->hasItems() &&
            $cart->getCarrier() instanceof CarrierInterface &&
            $cart->getShippingAddress() instanceof AddressInterface &&
            $this->shippableCarrierValidator->isCarrierValid($cart->getCarrier(), $cart, $cart->getShippingAddress()));
}

public function commitStep(OrderInterface $cart, Request $request): bool
{
    $form = $this->createForm($request, $cart);

    if ($form->isSubmitted()) {
        if ($form->isValid()) {
            $cart = $form->getData();

            $this->cartManager->persistCart($cart);

            return true;
        }

        throw new CheckoutException('Shipping Form is invalid', 'coreshop.ui.error.coreshop_checkout_shipping_form_invalid');
    }

    return false;
}

public function prepareStep(OrderInterface $cart, Request $request): array
{
    return [
        'form' => $this->createForm($request, $cart)->createView(),
    ];
}