Do not set @client_secret and @pk_key if order has no valid payments

lib/spree_frontend/controllers/spree/checkout_controller_decorator.rb

@@ -6,11 +6,17 @@ def self.prepended(base)
 
     def process_payments_and_set_keys
       @order.tap do |order|
+        @client_secret = nil
+        @pk_key = nil
+
         order.process_payments!
-        order.reload.payments.valid.where.not(intent_client_key: nil).last.tap do |payment|
-          @client_secret = payment.intent_client_key
-          @pk_key = payment.payment_method.preferred_publishable_key
+        last_valid_payment = order.reload.payments.valid.where.not(intent_client_key: nil).last
+
+        if last_valid_payment
+          @client_secret = last_valid_payment.intent_client_key
+          @pk_key = last_valid_payment.payment_method.preferred_publishable_key
         end
+
       end
     end
   end