Fatal error when saving custom CSS

Hi, great plugin! Only problem I have is that it displays a page with a fatal error when I try to save the CSS in the Edit CSS tab under Appearance:

Fatal error: Uncaught Error: Call to undefined function get_current_screen() in /home/neuronootropic/neuronootropic.com/wp-content/plugins/schema/includes/admin/ref.php:120 Stack trace: #0 /home/neuronootropic/neuronootropic.com/wp-content/plugins/schema/includes/misc-functions.php(414): schema_wp_update_meta_ref(2319) #1 /home/neuronootropic/neuronootropic.com/wp-includes/plugin.php(524): schema_wp_clear_json_on_post_save(2319, Object(WP_Post), true) #2 /home/neuronootropic/neuronootropic.com/wp-includes/post.php(3409): do_action(‘save_post’, 2319, Object(WP_Post), true) #3 /home/neuronootropic/neuronootropic.com/wp-includes/post.php(3482): wp_insert_post(Array, false) #4 /home/neuronootropic/neuronootropic.com/wp-content/plugins/jetpack/modules/custom-css/custom-css.php(478): wp_update_post(Array) #5 /home/neuronootropic/neuronootropic.com/wp-content/plugins/jetpack/modules/custom-css/custom-css.php(304): Jetpack_Custom_CSS::save_revision(‘/*\nWelcome to C…’, false, ”) #6 /home/neuronootropic/neuronootropic.com/wp-co in /home/neuronootropic/neuronootropic.com/wp-content/plugins/schema/includes/admin/ref.php on line 120

The CSS saves fine so it’s not breaking the site. Not sure how to fix it. Any ideas? Site is https://www.neuronootropic.com/ in case you need it.