Merx Shop Error after Updating from 1.5.1 to 1.6.1/1.6.2

I get the following error message when I want to do a checkout in the store:

I don’t understand why this function throws this error and why it is displayed as dump() in the UI.

Array
(
    [paymentmethod] => Array
        (
            [label] => Payment Method
            [message] => Array
                (
                    [required] => Bitte gib etwas ein
                )

        )

)

Dump from my OrderPage Object:

OrderPage Object
(
    [children] => Kirby\Cms\Pages Object
        (
        )

    [content] => Kirby\Cms\Content Object
        (
            [name] => Max MM Mustermann
            [email] => max@mustermann.de
            [street] => Musterstraße 16
            [zip] => 12345
            [city] => Musterhausen
            [country] => Deutschland
            [paymentmethod] => stripe-simple
            [legal] => on
            [items] => - 
  id: shop/xxx-2022-edition
  quantity: "1"
  key: >
    shop/xxx-2022-edition-weiss-ral9010
  color: weiß (RAL9010)
  title: 'xxx - 2022 Edition'
  price: 395
  taxRate: 19
  template: product
  uid: xxx-2022-edition
  tax: '63.067226890756'
  sum: 395
  sumTax: '63.067226890756'
- 
  id: shop/versandkosten
  key: shop/versandkosten
  quantity: 1
  title: Versandkosten
  price: 12
  taxRate: 19
  template: product
  uid: versandkosten
  tax: '1.9159663865546'
  sum: 12
  sumTax: '1.9159663865546'

        )

    [files] => Kirby\Cms\Files Object
        (
        )

    [id] => i5mmdvUX2nthsNEJ
    [mediaUrl] => https://xxx/media/shop/pages/i5mmdvUX2nthsNEJ
    [mediaRoot] => /Users/timo/projects/xxx/website/media/shop/pages/i5mmdvUX2nthsNEJ
    [num] => 
    [parent] => 
    [slug] => i5mmdvUX2nthsNEJ
    [template] => Kirby\Cms\Template Object
        (
            [name:protected] => order
            [type:protected] => html
            [defaultType:protected] => html
        )

    [translations] => Kirby\Cms\Collection Object
        (
            [0] => de
        )

    [uid] => i5mmdvUX2nthsNEJ
    [uri] => i5mmdvUX2nthsNEJ
    [url] => https://xxx/i5mmdvUX2nthsNEJ
    [siblings] => Kirby\Cms\Pages Object
        (
            [0] => home
            [1] => shop
            [2] => agb
            [3] => checkout
            [4] => datenschutzerklaerung
            [5] => error
            [6] => impressum
            [7] => orders
            [8] => success
            [9] => widerrufsbelehrung
        )

)

Settings:

'ww.merx.gateways' => [
		'pre-order'     => [
			'completePayment' => function (OrderPage $virtualOrderPage, array $data): OrderPage {

				// update order page
				$virtualOrderPage->content()->update([
					'paymentComplete' => false,
				]);
				return $virtualOrderPage;
			}
		],
		'stripe-simple' => [
			'initializePayment' => function (OrderPage $virtualOrderPage): OrderPage {

				setStripeApiKey();

				$items = [];
				foreach ($virtualOrderPage->cart() as $item) {

					$p = site()->find($item['id']);
					$title = ($p && $p->parent() && $p->parent()->intendedTemplate() == 'product') ? $p->parent()->title() . ' (' . $item['title'] . ')' : $item['title'];

					if (isset($item['color']))
						$title .= ' - ' . $item['color'];

					$items[] = [
						'price_data' => [
							'currency'     => option('ww.merx.currency', 'EUR'),
							'product_data' => [
								'name' => $title,
							],
							'unit_amount'  => floatval($item['sum']) * 100,
						],
						'quantity'   => $item['quantity'],
					];
				}

				$session = \Stripe\Checkout\Session::create([
					'customer_email' => $virtualOrderPage->email(),
					'line_items'     => $items,
					'mode'           => 'payment',
					'success_url'    => url(option('ww.merx.successPage') . '?session_id={CHECKOUT_SESSION_ID}'),
					'cancel_url'     => url('checkout'), // todo error Page?!
				]);

				$virtualOrderPage->content()->update([
					'sessionId' => $session->id,
					'session'   => $session,
					'redirect'  => $session->url,
				]);
				return $virtualOrderPage;
			},
			'completePayment'   => function (OrderPage $virtualOrderPage, array $data): OrderPage {

				setStripeApiKey();

				$session = null;
				$customer = null;

				// get session and customer data
				if ($virtualOrderPage->sessionId()->toString() === $data['session_id']) {
					$session = \Stripe\Checkout\Session::retrieve($data['session_id']);
					$customer = \Stripe\Customer::retrieve($session->customer);
				}

				// check if user canceled payment
				if ($session === null || $session['payment_status'] !== 'paid' || $session['status'] !== 'complete') {
					// throw new Exception([
					// 	'key'      => 'merx.paymentCanceled',
					// 	'httpCode' => 400,
					// ]);
				}

				// update order page
				$virtualOrderPage->content()->update([
					'paymentDetails'  => $session,
					'customer'        => $customer,
					'paymentComplete' => true,
					'payedDate'       => date('c'),
				]);
				return $virtualOrderPage;
			}
		],
	],

PHP 7.4.33 and PHP 8.1, Kirby 3.7.5.1

@tobiasfabian can you possibly help?

The problem has been fixed with Merx 1.7.0-beta.1.

/app # composer show
abraham/twitteroauth             3.3.0    The most popular PHP library for use with the Twitter OAuth REST API.
claviska/simpleimage             3.7.2    A PHP class that makes working with images as simple as possible.
composer/ca-bundle               1.3.5    Lets you find a path to the system CA bundle, and includes a fallback to the Mozilla CA bundle.
composer/semver                  3.3.2    Semver library that offers utilities, version constraint parsing and validation.
filp/whoops                      2.14.6   php error handling for cool kids
getkirby/cms                     3.9.1    The Kirby 3 core
getkirby/composer-installer      1.2.1    Kirby's custom Composer installer for the Kirby CMS and for Kirby plugins
hashandsalt/kirby3-twitter       v1.0.3   Kirby Twitter Plugin
laminas/laminas-escaper          2.12.0   Securely and safely escape HTML, HTML attributes, JavaScript, CSS, and URLs
league/color-extractor           0.3.2    Extract colors from an image as a human would do.
medienbaecker/kirby-autofavicon  1.0.2    Kirby AutoFavicon
medienbaecker/kirby-modules      2.4.0    Easily add modules to your pages
michelf/php-smartypants          1.8.1    PHP SmartyPants
paypal/paypal-checkout-sdk       1.0.2    PayPal's PHP SDK for Checkout REST APIs
paypal/paypalhttp                1.0.1   
phpmailer/phpmailer              v6.7.1   PHPMailer is a full-featured email creation and transfer class for PHP
psr/log                          3.0.0    Common interface for logging libraries
schnti/autoresize                0.1.2    Kirby Autoresize Plugin
schnti/cachebuster               1.0.3    A plugin for Kirby 3 CMS to add modification timestamps to css and js files
schnti/legal                     0.1.1    kirby legal plugin
schnti/photoswipe                1.0.1    A plugin for Kirby 3 CMS to intecrate photoswipe
schnti/sitemap                   2.0.0    kirby sitemap plugin
schnti/video                     1.3.0    kirby privacy video tag
stripe/stripe-php                v7.128.0 Stripe PHP Library
symfony/polyfill-intl-idn        v1.27.0  Symfony polyfill for intl's idn_to_ascii and idn_to_utf8 functions
symfony/polyfill-intl-normalizer v1.27.0  Symfony polyfill for intl's Normalizer class and related functions
symfony/polyfill-mbstring        v1.27.0  Symfony polyfill for the Mbstring extension
wagnerwagner/merx                1.6.2    A toolkit to create online shops with Kirby 3