[FIX] website_sale_delivery: don't replace error message by 'Free'

When a delivery carrier can't compute the delivery price, it returns an error
that is shown instead of the price (eg 'bpost Domestic is used only to ship
inside Belgium..').

But since 1ab53c27f everytime the user compute a carrier price and there is a
coupon allowing free delivery, every listed delivery carrier would have their
badges set to 'Free', including also carrier in error state.

This commit will not replace the error message by 'Free'.

Coming from #31857 (task-1867265)

addons/website_sale_delivery/static/src/js/website_sale_delivery.js

@@ -51,8 +51,9 @@ publicWidget.registry.websiteSaleDelivery = publicWidget.Widget.extend({
             // Update discount of the order
             $('#order_discounted').find('.oe_currency_value').text(result.new_amount_order_discounted);
 
-            // We are in freeshipping, so every carrier is Free
-            $('#delivery_carrier .badge').text(_t('Free'));
+            // We are in freeshipping, so every carrier is Free but we don't
+            // want to replace error message by 'Free'
+            $('#delivery_carrier .badge:not(.o_wsale_delivery_carrier_error)').text(_t('Free'));
         }
 
         if (result.status === true) {
@@ -63,10 +64,12 @@ publicWidget.registry.websiteSaleDelivery = publicWidget.Widget.extend({
             $carrierBadge.children('span').text(result.new_amount_delivery);
             $carrierBadge.removeClass('d-none');
             $computeBadge.addClass('d-none');
+            $computeBadge.removeClass('o_wsale_delivery_carrier_error');
             $payButton.data('disabled_reasons').carrier_selection = false;
             $payButton.prop('disabled', _.contains($payButton.data('disabled_reasons'), true));
         } else {
             console.error(result.error_message);
+            $computeBadge.addClass('o_wsale_delivery_carrier_error');
             $computeBadge.text(result.error_message);
             $amountDelivery.text(result.new_amount_delivery);
             $amountUntaxed.text(result.new_amount_untaxed);