Getting an error

Hi,

I was updating a product and when I wanted to save it, it kept going. The problem is this plugin. I got this error message

Een fout van het type?E_ERROR?trad op op lijn?489?in het bestand?/wp-content/plugins/show-product-variations-for-woocommerce/admin/class-wsv-admin.php. Foutmelding:?Uncaught TypeError: array_unique(): Argument #1 ($array) must be of type array, null given in /wp-content/plugins/show-product-variations-for-woocommerce/admin/class-wsv-admin.php:489 Stack trace: #0 /wp-content/plugins/show-product-variations-for-woocommerce/admin/class-wsv-admin.php(489): array_unique(NULL) #1 /wp-includes/class-wp-hook.php(326): Wsv_Admin->save_post(299) #2 /wp-includes/class-wp-hook.php(348): WP_Hook->apply_filters('', Array) #3 /wp-includes/plugin.php(517): WP_Hook->do_action(Array) #4 /wp-content/plugins/woocommerce/includes/admin/class-wc-admin-meta-boxes.php(273): do_action('...', 299, Object(WP_Post)) #5 /wp-includes/class-wp-hook.php(326): WC_Admin_Meta_Boxes->save_meta_boxes(299, Object(WP_Post)) #6 /wp-includes/class-wp-hook.php(348): WP_Hook->apply_filters('', Array) #7 /wp-includes/plugin.php(517): WP_Hook->do_action(Array) #8 /wp-includes/post.php(4760): do_action('...', 299, Object(WP_Post), true) #9 /wp-includes/post.php(4862): wp_insert_post(Array, false, true) #10 /wp-admin/includes/post.php(453): wp_update_post(Array) #11 /wp-admin/post.php(227): edit_post() #12 {main} thrown