prevent saving the enterprise fee when a per order calculator is selected along with 'Inherit from product'

app/models/enterprise_fee.rb

@@ -58,6 +58,14 @@ class EnterpriseFee < ApplicationRecord
     elsif inherits_tax_category_changed?
       self.tax_category_id = nil if inherits_tax_category?
     end
+
+    if inherits_tax_category? && PER_ORDER_CALCULATORS.include?(calculator_type)
+      errors.add(:inherits_tax_category,
+                 I18n.t("activerecord.errors.models." \
+                  "enterpise_fee.cannot_inherit_from_product_when_per_order_calculator_selected"))
+      throw :abort
+    end
+
     true
   end
 end

config/locales/en.yml

@@ -113,7 +113,8 @@ en:
             using_producer_stock_settings_but_count_on_hand_set: "must be blank because using producer stock settings"
             on_demand_but_count_on_hand_set: "must be blank if on demand"
             limited_stock_but_no_count_on_hand: "must be specified because forcing limited stock"
-
+        enterpise_fee:
+          cannot_inherit_from_product_when_per_order_calculator_selected: "You cannot select 'Inherit From Product' when a per order calculator is selected"
   # Used by active_storage_validations
   errors:
     messages: