Initialize instance variables when finish

Signed-off-by: Kenji Okimoto <okimoto@clear-code.com>

app/controllers/concerns/setting_concern.rb

@@ -17,6 +17,8 @@ module SettingConcern
 
   def finish
     @setting = target_class.new(setting_params)
+    @_used_param = {}
+    @_used_section = {}
     unless @setting.valid?
       return render "shared/settings/show"
     end