Placeholder fallback. Unescaped output comment.

Author: Igloczek

app/code/Magento/Catalog/Block/Product/View/Gallery.php

@@ -233,4 +233,19 @@ private function getGalleryImagesConfig()
 
         return $this->getData('gallery_images_config');
     }
+
+    /**
+     * @param string $image
+     * @return string
+     */
+    public function getMainProductImage()
+    {
+        $image = $this->getGalleryImages()->toArray()['items'][0]['medium_image_url'];
+
+        if (!$image) {
+            return $this->_imageHelper->getDefaultPlaceholderUrl('image');
+        }
+
+        return $image;
+    }
 }

app/code/Magento/Catalog/view/frontend/templates/product/view/gallery.phtml

@@ -13,12 +13,10 @@
  */
 ?>
 
-<?php $images = $block->getGalleryImages()->toArray()['items'] ?>
-
 <div class="gallery-placeholder _block-content-loading" data-gallery-role="gallery-placeholder">
     <img
         class="gallery-placeholder__image"
-        src="<?= $images[0]['medium_image_url'] ?>"
+        src="<?= /* @escapeNotVerified */ $block->getMainProductImage() ?>"
     />
 </div>