Plugin not responding

Getting this error on the backend.

Fatal error: Uncaught Error: Call to a member function get_name() on bool in /usr/www/users/bigbeuzftp/creationswithlove2.bigbeardbeta.co.za/wp-content/plugins/product-size-chart-for-woo/admin/design-new.php:918 Stack trace: #0 /usr/www/users/bigbeuzftp/creationswithlove2.bigbeardbeta.co.za/wp-includes/class-wp-hook.php(309): PSCW_PRODUCT_SIZE_CHART_F_WOO_Design->show_custom_columns('assign_cate') #1 /usr/www/users/bigbeuzftp/creationswithlove2.bigbeardbeta.co.za/wp-includes/class-wp-hook.php(331): WP_Hook->apply_filters('', Array) #2 /usr/www/users/bigbeuzftp/creationswithlove2.bigbeardbeta.co.za/wp-includes/plugin.php(476): WP_Hook->do_action(Array) #3 /usr/www/users/bigbeuzftp/creationswithlove2.bigbeardbeta.co.za/wp-admin/includes/class-wp-posts-list-table.php(1349): do_action('manage_pscw-siz...', 'assign_cate', 2063) #4 /usr/www/users/bigbeuzftp/creationswithlove2.bigbeardbeta.co.za/wp-admin/includes/class-wp-list-table.php(1450): WP_Posts_List_Table->column_default(Object(WP_Post), 'assign_cate') #5 /usr/www/users/ in /usr/www/users/bigbeuzftp/creationswithlove2.bigbeardbeta.co.za/wp-content/plugins/product-size-chart-for-woo/admin/design-new.php on line 918

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