fix error

app/controllers/admin/asks_controller.rb

@@ -285,7 +285,7 @@ class Admin::AsksController < OrbitAdminController
           all_to_save += [[k,AskFile.new(file: file,ask_question_id: @ask_question.id)]]
         end
       else
-        temp_params['custom_values'][k] = @ask_question.custom_values[k]
+        temp_params['custom_values'][k] = @ask_question.custom_values[k] rescue nil
       end
     end
     flag = @ask_question.save