Fix issue with new guest details section

The component was checking for a street field. For the new guest
details section this isn't available. So for that reason an additional
check has been added to skip further logic if there is no "street"
field.

Model/Form/Modifier/AddHousenumberFieldValidation.php

@@ -5,6 +5,7 @@
 
 namespace Vendic\HyvaCheckoutGoogleAddressAutocomplete\Model\Form\Modifier;
 
+use Hyva\Checkout\Model\Form\EntityFormElementInterface;
 use Hyva\Checkout\Model\Form\EntityFormInterface;
 use Hyva\Checkout\Model\Form\EntityFormModifierInterface;
 
@@ -26,6 +27,10 @@ public function apply(EntityFormInterface $form): EntityFormInterface
             function (EntityFormInterface $form) {
                 $street = $form->getElement('street');
 
+                if (!$street instanceof EntityFormElementInterface) {
+                    return;
+                }
+
                 $relatives = $street->getRelatives();
 
                 // Check if there is only one relative, if not, we don't have a housenumber field