Need Help with Shopify Plugin: Buy Button Not Working

Hello, I’m working on a project using the Shopify plugin.
I’ve successfully implemented most of the features following the Shopify plugin manual, but I’m having trouble with the Buy Button; it’s not working.
Is there anyone who can help me with this issue?
Here are the error details and the code…!
*** For reference, there are no issues with the domain and storefrontAccessToken.

Link: https://1-2-3-4-5.studio/typeface/products/yoonseul-batang

/templates/shopify.product.php

<!-- Display values with Kirby if you want -->
<img src="<?= $page->shopifyFeatured() ?>" />
<?= $page->yourCustomField() ?>
<?= $page->shopifyPrice() ?>
<?= $page->shopifyDescriptionHTML() ?>
<?= $page->shopifyType() ?>
<?= $page->shopifyVendor() ?>

<!-- Shopify Product Button -->
<div id="product-component-<?= $productID ?>"></div>

<?php foreach ($page->shopifyTags()->split(',') as $key => $tag): ?>
  <?= $tag ?>
<?php endforeach ?>

/snippets/Footer.php

  <script>
       <?php
// PHP variables for Shopify product data
$producttitle = $page->shopifyTitle();
$producttext = $page->shopifyDescriptionHTML();
$productimage = $page->shopifyFeaturedImage();
$productID = $page->shopifyID();
$productprice = $page->shopifyPrice();
$productbuttontext = 'Buy Now';
$productimagealt = $producttitle;
?>
     </script>
<div id="product-component-<?= $productID ?>"></div>
     <script src="https://sdks.shopifycdn.com/buy-button/2.4.0/buybutton.min.js"></script>

<script type="text/javascript">

(function () {
  var scriptURL = 'https://sdks.shopifycdn.com/buy-button/latest/buy-button-storefront.min.js';
  if (window.ShopifyBuy) {
    if (window.ShopifyBuy.UI) {
      ShopifyBuyInit();
    } else {
      loadScript();
    }
  } else {
    loadScript();
  }

  function loadScript() {
    var script = document.createElement('script');
    script.async = true;
    script.src = scriptURL;
    (document.getElementsByTagName('head')[0] || document.getElementsByTagName('body')[0]).appendChild(script);
    script.onload = ShopifyBuyInit;
  }

  function ShopifyBuyInit() {
    var client = ShopifyBuy.buildClient({
      domain: 'xxxxx.myshopify.com',
      storefrontAccessToken: 'shpat_xxxxxxxxxxxxxxxxx',
      appId: '15'
    });

    ShopifyBuy.UI.onReady(client).then(function (ui) {
      ui.createComponent('product', {
        id: <?= $productID ?>,
        node: document.getElementById('product-component-<?= $productID ?>'),
        moneyFormat: '%24%24%24%7B%7Bamount%7D%7D',
        options: {
          "product": {
            "variantId": "all",
            "contents": {
              "variantTitle": false,
              "description": false,
              "buttonWithQuantity": false,
              "quantity": false
            },
            "styles": {
              "product": {
                "@media (min-width: 601px)": {
                  "max-width": "calc(25% - 20px)",
                  "margin-left": "20px",
                  "margin-bottom": "50px"
                }
              }
            }
          },
          "cart": {
            "contents": {
              "button": true
            },
            "styles": {
              "footer": {
                "background-color": "#ffffff"
              }
            }
          },
          "modalProduct": {
            "contents": {
              "variantTitle": false,
              "buttonWithQuantity": false,
              "quantity": false
            },
            "styles": {
              "product": {
                "@media (min-width: 601px)": {
                  "max-width": "100%",
                  "margin-left": "0px",
                  "margin-bottom": "0px"
                }
              }
            }
          },
          "productSet": {
            "styles": {
              "products": {
                "@media (min-width: 601px)": {
                  "margin-left": "-20px"
                }
              }
            }
          }
        }
      });
    });
  }
})();
</script>

Have you checked with e.g. console.log() what ShopifyBuy.UI at that moment contains?