fix: calculate with empty fields

src/classes/class-exprdawc-product-page-fronted.php

@@ -551,6 +551,9 @@ class Exprdawc_Product_Page_Fronted {
 			if ( isset( $cart_item['extra_user_data'] ) ) {
 				foreach ( $cart_item['extra_user_data'] as $user_data ) {
 					$price_adjustment = 0;
+					if ( ( empty( $user_data['value'] ) ) ) {
+						continue;
+					}
 					if ( $user_data['field_raw']['adjust_price'] ) {
 						if ( in_array( $user_data['field_raw']['type'], array( 'checkbox', 'radio', 'select' ), true ) ) {
 							$total_adjustment = 0;