use Invoice#latest to fetch the most recent invoice

app/models/invoice.rb

@@ -9,6 +9,10 @@ class Invoice < ApplicationRecord
   after_create :cancel_previous_invoices
   default_scope { order(created_at: :desc) }
 
+  def self.latest
+    reorder(created_at: :desc).first
+  end
+
   def presenter
     @presenter ||= Invoice::DataPresenter.new(self)
   end

app/services/order_invoice_generator.rb

@@ -13,7 +13,7 @@ class OrderInvoiceGenerator
         data: invoice_data
       )
     elsif comparator.can_update_latest_invoice?
-      order.invoices.first.update!(
+      order.invoices.latest.update!(
         date: Time.zone.today,
         data: invoice_data
       )