Error in administration => Redmine 3.4.13.

[FutureMarket]

Dear @fanzai0403!
I would like to use your plugin in redmine 3.4.13, but after i cant open the plugin configure menu.
This is the log:

Rendered settings/plugin.html.erb within layouts/admin (23.3ms)
App 26612 output: Completed 500 Internal Server Error in 93ms (ActiveRecord: 59.2ms)
App 26612 output:
App 26612 output: ActionView::Template::Error (undefined method []' for nil:NilClass): App 26612 output: 25: <td><%= h(status.name) %></td> App 26612 output: 26: <td align="center"> App 26612 output: 27: <%= select_tag("settings[status_assigned_to][#{status.id}]", App 26612 output: 28: principals_options_for_select(scope, settings['status_assigned_to'][status.id.to_s]), App 26612 output: 29: :include_blank => true) %> App 26612 output: 30: App 26612 output: 31: </td> App 26612 output: plugins/status_button/app/views/settings/_status_button_settings.html.erb:28:in block in _plugins_status_button_app_views_settings__status_button_settings_html_er$
App 26612 output: plugins/status_button/app/views/settings/_status_button_settings.html.erb:23:in _plugins_status_button_app_views_settings__status_button_settings_html_erb__425570$ App 26612 output: app/views/settings/plugin.html.erb:6:in block in _app_views_settings_plugin_html_erb__3520017754572066799_47183153145800'
App 26612 output: app/views/settings/plugin.html.erb:4:in _app_views_settings_plugin_html_erb__3520017754572066799_47183153145800' App 26612 output: lib/redmine/sudo_mode.rb:63:in sudo_mode'

Thanks a lot for your work!

Jenci