fixup! [Bexley][WW] Update displayed GGW bin costs and total depdendi…

…ng on if DD or not.

Fix price display on form error.

web/cobrands/bexley/waste.js

@@ -3,5 +3,15 @@ window.garden_waste_first_bin_discount_applies = function() {
 };
 
 $(function() {
+    // If there's an error when submitting the subscribe form,
+    // the first bin discount won't be displayed even when it should apply.
+    // This is due to how the form is set-up on the server.
+    // We work around this by just checking if the discount should apply
+    // when the page loads and running the cost calculation function if so.
+    window.onload = function() {
+        if (window.garden_waste_first_bin_discount_applies()) {
+            window.garden_waste_bin_cost_new();
+        }
+    };
     $('#subscribe_details input[name="payment_method"]').on('change', window.garden_waste_bin_cost_new);
 });