fix(foxy-experimental-add-to-cart-builder): fix undefined appearing as custom option value when freeform input is enabled and no default value is provided

Author: pheekus

src/elements/public/ExperimentalAddToCartBuilder/ExperimentalAddToCartBuilder.ts

@@ -759,7 +759,7 @@ export class ExperimentalAddToCartBuilder extends Base<Data> {
           const optionIndex = product.custom_options.indexOf(group[0]);
           const itemCategory = this.__getItemCategoryLoader(productIndex, optionIndex)?.data;
           const modifiers = this.__getOptionModifiers(group[0], itemCategory ?? null, currencyCode);
-          const value = `${group[0].value}${modifiers}`;
+          const value = `${group[0].value ?? ''}${modifiers}`;
           const name = `${prefix}${optionName}`;
 
           if (group[0].value_configurable) {
@@ -790,7 +790,10 @@ export class ExperimentalAddToCartBuilder extends Base<Data> {
             const optionIndex = product.custom_options.indexOf(option);
             const itemCategory = this.__getItemCategoryLoader(productIndex, optionIndex)?.data;
             const modifiers = this.__getOptionModifiers(option, itemCategory ?? null, currencyCode);
-            const encodedValue = encodeAttributeValue(`${option.value}${modifiers}`, isHmacOn);
+            const encodedValue = encodeAttributeValue(
+              `${option.value ?? ''}${modifiers}`,
+              isHmacOn
+            );
             const encodedCaption = encode(option.value ?? '');
             output += `${newline()}<option value="${encodedValue}">${encodedCaption}</option>`;
           });