Don't try to use mail attribute if invalid

app/models/application_record.rb

@@ -7,6 +7,14 @@ class ApplicationRecord < ::ActiveRecord::Base
     saved_change_to_attribute?(:id)
   end
 
+  ##
+  # Returns whether the given attribute is free of errors
+  def valid_attribute?(attribute)
+    valid? # Ensure validations have run
+
+    errors[attribute].empty?
+  end
+
   ##
   # Get the newest recently changed resource for the given record classes
   #

app/services/users/set_attributes_service.rb

@@ -42,7 +42,7 @@ module Users
 
     def set_default_attributes(_params)
       # Assign values other than mail to new_user when invited
-      if model.invited? && model.mail.present?
+      if model.invited? && model.valid_attribute?(:mail)
         ::UserInvitation.assign_user_attributes model
       end