Replace #raise with #return in Checkout::StripeRedirect

The (potential) unhappy code path here was raising an error which would not be explicitly handled, and would in theory not return a useful message / response.

app/controllers/checkout_controller.rb

@@ -178,6 +178,7 @@ class CheckoutController < ::BaseController
       if @order.state == "payment"
         return if redirect_to_payment_gateway
 
+        return action_failed if @order.errors.any?
         return action_failed unless @order.process_payments!
       end
 

app/services/checkout/stripe_redirect.rb

@@ -16,7 +16,7 @@ module Checkout
 
       payment = payment_authorizer.call!(return_url)
 
-      raise if order.errors.any?
+      return if order.errors.any?
 
       stripe_payment_url(payment)
     end