WordPress Issue

Hi there,
I’m recieving this issue in E-mail kindly see it:

An error of type E_ERROR was caused in line 254 of the file /var/www/wp-content/plugins/woocommerce-free-shipping-bar/includes/data.php. Error message: Uncaught Error: Call to a member function get() on null in /var/www/wp-content/plugins/woocommerce-free-shipping-bar/includes/data.php:254
Stack trace:
#0 /var/www/wp-content/plugins/woocommerce-free-shipping-bar/includes/data.php(732): WFSPB_Data->get_free_shipping_min_amount()
#1 /var/www/wp-content/plugins/woocommerce-free-shipping-bar/wfspb-front-end.php(346): WFSPB_Data->enqueue_script_frontend()
#2 /var/www/wp-includes/class-wp-hook.php(303): WFSPB_FrontEnd->enqueue_script_for_main_bar(”)
#3 /var/www/wp-includes/class-wp-hook.php(327): WP_Hook->apply_filters(NULL, Array)
#4 /var/www/wp-includes/plugin.php(470): WP_Hook->do_action(Array)
#5 /var/www/wp-includes/script-loader.php(2083): do_action(‘wp_enqueue_scri…’)
#6 /var/www/wp-includes/class-wp-hook.php(303): wp_enqueue_scripts(”)
#7 /var/www/wp-includes/class-wp-hook.php(327): WP_Hook->apply_filters(NULL, Array)
#8 /var/www/wp-includes/plugin.php(470): WP_Hook->do_action(Array)
#9 /var/www/wp-includes/general-template.php(3015): do_action(‘wp_hea

Thanks