fatal error

Can you fix on this? I have recently met it everyday

2023-10-30T23:37:32+00:00 CRITICAL Uncaught Error: Call to a member function get_code() on null in /usr/share/nginx/wordpress/wp-content/plugins/discount-and-dynamic-pricing/public/class-thwdpf-public-discount-cart.php:137 Stack trace: #0 /usr/share/nginx/wordpress/wp-includes/class-wp-hook.php(308): THWDPF_Public_Discount_Cart->remove_coupon_errors() #1 /usr/share/nginx/wordpress/wp-includes/plugin.php(205): WP_Hook->apply_filters() #2 /usr/share/nginx/wordpress/wp-content/plugins/woocommerce/includes/class-wc-coupon.php(1098): apply_filters() #3 /usr/share/nginx/wordpress/wp-content/plugins/woocommerce/includes/class-wc-ajax.php(252): WC_Coupon::get_generic_coupon_error() #4 /usr/share/nginx/wordpress/wp-includes/class-wp-hook.php(308): WC_AJAX::apply_coupon() #5 /usr/share/nginx/wordpress/wp-includes/class-wp-hook.php(332): WP_Hook->apply_filters() #6 /usr/share/nginx/wordpress/wp-includes/plugin.php(517): WP_Hook->do_action() #7 /usr/share/nginx/wordpress/wp-content/plugins/woocommerce/includes/class-wc-ajax.php(96): do_action() #8 /usr/share/nginx/wordpress/wp-includes/class-wp-hook.php(308): WC_AJAX::do_wc_ajax() #9 /usr/share/nginx/wordpress/wp-includes/class-wp-hook.php(332): WP_Hook->apply_filters() #10 /usr/share/nginx/wordpress/wp-includes/plugin.php(517): WP_Hook->do_action() #11 /usr/share/nginx/wordpress/wp-includes/template-loader.php(13): do_action() #12 /usr/share/nginx/wordpress/wp-blog-header.php(19): require_once(‘…’) #13 /usr/share/nginx/wordpress/index.php(17): require(‘…’) #14 {main} thrown in /usr/share/nginx/wordpress/wp-content/plugins/discount-and-dynamic-pricing/public/class-thwdpf-public-discount-cart.php on line 137