Undefined constant “left” in /genesis-slide-in-widget/inc/gsw-admin.php

After editing Slide-in menu options, Slide-in menus look very malformed.
I also receive this error:

An error of type E_ERROR was caused in line 149 of the file /nas/content/live/averostaging/wp-content/plugins/genesis-slide-in-widget/inc/gsw-admin.php. Error message: Uncaught Error: Undefined constant "left" in /nas/content/live/averostaging/wp-content/plugins/genesis-slide-in-widget/inc/gsw-admin.php:149
Stack trace:
#0 /nas/content/live/averostaging/wp-admin/includes/template.php(1395): WPSTUDIO_gsw_Settings->gsw_settings(NULL, Array)
#1 /nas/content/live/averostaging/wp-content/themes/genesis/lib/views/misc/genesis-admin-boxes-holder.php(27): do_meta_boxes(Object(WP_Screen), 'main', NULL)
#2 /nas/content/live/averostaging/wp-content/themes/genesis/lib/classes/class-genesis-admin-boxes.php(74): include('/nas/content/li...')
#3 /nas/content/live/averostaging/wp-includes/class-wp-hook.php(307): Genesis_Admin_Boxes->do_metaboxes('genesis_page_ge...')
#4 /nas/content/live/averostaging/wp-includes/class-wp-hook.php(331): WP_Hook->apply_filters('', Array)
#5 /nas/content/live/averostaging/wp-includes/plugin.php(474): WP_Hook->do_action(Array)
#6 /nas/content/live/averostaging/wp-content/themes/genesis/lib/views/pages/genesis-admin-boxes.php(35): do_action('genesis_page_ge...', 'genesis_page_ge...')
#7 /nas/content/live/averostaging/wp-content/themes/genesis/lib/classes/class-genesis-admin-boxes.php(57): include('/nas/content/li...')
#8 /nas/content/live/averostaging/wp-includes/class-wp-hook.php(307): Genesis_Admin_Boxes->admin('')
#9 /nas/content/live/averostaging/wp-includes/class-wp-hook.php(331): WP_Hook->apply_filters('', Array)
#10 /nas/content/live/averostaging/wp-includes/plugin.php(474): WP_Hook->do_action(Array)
#11 /nas/content/live/averostaging/wp-admin/admin.php(259): do_action('genesis_page_ge...')
#12 {main}
  thrown

Additional info about our environment:
WordPress version 5.9.3
Current theme: Genesis Sample (version 3.1.0) Current plugin: Genesis Slide-in Widget (version 1.5) PHP version 8.0.17

I also noticed that “Settings panel” section of the “Genesis Slide-in Widget Settings” page is missing. Specifically where slide from option is defined, as the error suggest.

I suspect this plugin needs to be updated for compatibility with newer version of WordPress. Is this a possibility in the near future?

The page I need help with: [log in to see the link]