Return 404 when order is not found

Current implementation is very happy-path oriented. When order exists,
everything is fine. However, when there is no order, then the
NoMethodError (as in honeybadger) is thrown.

The behaviour is changed now. The 404 page is returned when
there is no order for given id.

https://app.honeybadger.io/projects/58419/faults/91462781/01J3Y753P7F6F70CYT2ZQE1VND
#342

rails_application/app/controllers/orders_controller.rb

@@ -5,6 +5,9 @@ def index
 
   def show
     @order = Orders::Order.find_by_uid(params[:id])
+
+    return not_found unless @order
+
     @order_lines = Orders::OrderLine.where(order_uid: @order.uid)
     @shipment = Shipments::Shipment.find_by(order_uid: @order.uid)
     @invoice = Invoices::Invoice.find_or_initialize_by(order_uid: @order.uid)
@@ -128,4 +131,8 @@ def authorize_payment_cmd(order_id)
   def capture_payment_cmd(order_id)
     Payments::CapturePayment.new(order_id: order_id)
   end
+
+  def not_found
+    render file: "#{Rails.root}/public/404.html", layout: false, status: :not_found
+  end
 end

rails_application/test/integration/orders_test.rb

@@ -104,6 +104,11 @@ def test_expiring_orders
     assert_select("td", "Expired")
   end
 
+  def test_order_not_found
+    get "/orders/123"
+    assert_response :not_found
+  end
+
   def test_cancel
     shopify_id = register_customer("Shopify")