adds translation key to the included in price validation

app/models/spree/tax_rate.rb

@@ -7,7 +7,7 @@ module Spree
 
       return if Zone.default_tax
 
-      record.errors.add(:included_in_price, Spree.t(:included_price_validation))
+      record.errors.add(:included_in_price, Spree.t("errors.messages.included_price_validation"))
     end
   end
 end

config/locales/en.yml

@@ -3221,6 +3221,7 @@ See the %{link} to find out more about %{sitename}'s features and to start using
         payment_state: "Payment State"
     errors:
       messages:
+        included_price_validation: "cannot be selected unless you have set a Default Tax Zone"
         blank: "can't be blank"
     layouts:
       admin: