MeanMenu plugin does not working

Hi!

I used the 8.x-1.x-dev module version. When i tried to use MeanMenu plugin (save the settings on condig page: admin/config/user-interface/responsive_menus) i received the errors in my site log :

Warning: call_user_func() expects parameter 1 to be a valid callback, function '_drupal_add_css' not found or invalid function name in libraries_load_files() (line 735 of ..../modules/libraries/libraries.module).

User error: Invalid placeholder (!bars) in string: Default of 3 spans will show the triple bars (!bars). in Drupal\Component\Render\FormattableMarkup::placeholderFormat() (line 233 of ....../core/lib/Drupal/Component/Render/FormattableMarkup.php).

Looks like something goes wrong in config page submit for MeanMenu. Also, the plugin does not working on all site pages.

When i tried to use simple expanded plugin - all works fine, but it does not have collapsible menu subitems.