Plugin triggered the fatal error in WordPress 5.2

An error of type E_ERROR was caused in line 29 of the file /home/s762/html/wp-content/plugins/coupon-by-roles-for-woocommerce/inc/coupon-by-roles-woocommerce.php. Error message: Uncaught Error: Call to undefined function coupon_get_roles_names() in /home/s762/html/wp-content/plugins/coupon-by-roles-for-woocommerce/inc/coupon-by-roles-woocommerce.php:29
Stack trace:
#0 /home/s762/html/wp-includes/class-wp-hook.php(284): Coupon_By_Roles_WC->add_coupon_user_roles_list()
#1 /home/s762/html/wp-includes/class-wp-hook.php(310): WP_Hook->apply_filters(”, Array)
#2 /home/s762/html/wp-includes/plugin.php(465): WP_Hook->do_action(Array)
#3 /home/s762/html/wp-content/plugins/woocommerce/includes/admin/meta-boxes/class-wc-meta-box-coupon-data.php(280): do_action(‘woocommerce_cou…’, 9004111222002045, Object(WC_Coupon))
#4 /home/s762/html/wp-admin/includes/template.php(1304): WC_Meta_Box_Coupon_Data::output(Object(WP_Post), Array)
#5 /home/s762/html/wp-admin/edit-form-advanced.php(642): do_meta_boxes(Object(WP_Screen), ‘normal’, Object(WP_Post))
#6 /home/s762/html/wp-admin/post-new.php(75): include(‘/home/s762/html…’)
#7 {main}
thrown