ENGCOM-4362: Fix empty cart validation #21295

 - Merge Pull Request #21295 from wojtekn/magento2:fix_empty_cart_validation
 - Merged commits:
   1. 4cdcb74
   2. f6656f9
   3. 96793fe
   4. f82299b
   5. a1578b5

Author: magento-engcom-team

app/code/Magento/Checkout/view/frontend/templates/cart/form.phtml

@@ -14,7 +14,8 @@
           method="post"
           id="form-validate"
           data-mage-init='{"Magento_Checkout/js/action/update-shopping-cart":
-              {"validationURL" : "/checkout/cart/updateItemQty"}
+              {"validationURL" : "/checkout/cart/updateItemQty",
+              "updateCartActionContainer": "#update_cart_action_container"}
           }'
           class="form form-cart">
     <?= $block->getBlockHtml('formkey') ?>

app/code/Magento/Checkout/view/frontend/web/js/action/update-shopping-cart.js

@@ -14,7 +14,8 @@ define([
     $.widget('mage.updateShoppingCart', {
         options: {
             validationURL: '',
-            eventName: 'updateCartItemQty'
+            eventName: 'updateCartItemQty',
+            updateCartActionContainer: ''
         },
 
         /** @inheritdoc */
@@ -31,7 +32,9 @@ define([
          * @return {Boolean}
          */
         onSubmit: function (event) {
-            if (!this.options.validationURL) {
+            var action = this.element.find(this.options.updateCartActionContainer).val();
+
+            if (!this.options.validationURL || action === 'empty_cart') {
                 return true;
             }