Address CodeClimate complains

app/controllers/checkout_controller.rb

@@ -26,15 +26,15 @@ class CheckoutController < Spree::CheckoutController
           return if redirect_to_paypal_express_form_if_needed
         end
 
-        unless advance_order_state(@order)
-          if @order.errors.present?
-            flash[:error] = @order.errors.full_messages.to_sentence
-          else
-            flash[:error] = t(:payment_processing_failed)
-          end
-          update_failed
-          return
+        next if advance_order_state(@order)
+
+        if @order.errors.present?
+          flash[:error] = @order.errors.full_messages.to_sentence
+        else
+          flash[:error] = t(:payment_processing_failed)
         end
+        update_failed
+        return
       end
       if @order.state == "complete" ||  @order.completed?
         set_default_bill_address

app/controllers/spree/admin/payments_controller_decorator.rb

@@ -5,7 +5,7 @@ Spree::Admin::PaymentsController.class_eval do
   # When a user fires an event, take them back to where they came from
   # (we can't use respond_override because Spree no longer uses respond_with)
   def fire
-    return unless event = params[:e] and @payment.payment_source
+    return unless event = params[:e] && @payment.payment_source
 
     # Because we have a transition method also called void, we do this to avoid conflicts.
     event = "void_transaction" if event == "void"
@@ -15,7 +15,7 @@ Spree::Admin::PaymentsController.class_eval do
       flash[:error] = t(:cannot_perform_operation)
     end
   rescue Spree::Core::GatewayError => ge
-    flash[:error] = "#{ge.message}"
+    flash[:error] = ge.message
   ensure
     redirect_to request.referer
   end