Fatal error: Uncaught TypeError: method_exists(): Argument #1 ($object_or_class) must be of type object|string, null given in /homepages/31/d841462698/htdocs/clickandbuilds/AliMall/wp-content/plugins/groupby-for-woocommerce/public/class-wc-groupbuy-public.php:828 Stack trace: #0 /homepages/31/d841462698/htdocs/clickandbuilds/AliMall/wp-content/plugins/groupby-for-woocommerce/public/class-wc-groupbuy-public.php(828): method_exists(NULL, 'get_type') #1 /homepages/31/d841462698/htdocs/clickandbuilds/AliMall/wp-includes/class-wp-hook.php(309): wc_groupbuy_Public->add_post_class(Array) #2 /homepages/31/d841462698/htdocs/clickandbuilds/AliMall/wp-includes/plugin.php(189): WP_Hook->apply_filters(Array, Array) #3 /homepages/31/d841462698/htdocs/clickandbuilds/AliMall/wp-includes/post-template.php(581): apply_filters('post_class', Array, Array, 4368) #4 /homepages/31/d841462698/htdocs/clickandbuilds/AliMall/wp-includes/post-template.php(459): get_post_class(Array, NULL) #5 /homepages/31/d841462698/htdocs/clickandbuilds/AliMall/wp-content/themes/storefront/content-page.php(10): post_class() #6 /homepages/31/d841462698/htdocs/clickandbuilds/AliMall/wp-includes/template.php(772): require('/homepages/31/d...') #7 /homepages/31/d841462698/htdocs/clickandbuilds/AliMall/wp-includes/template.php(716): load_template('/homepages/31/d...', false, Array) #8 /homepages/31/d841462698/htdocs/clickandbuilds/AliMall/wp-includes/general-template.php(204): locate_template(Array, true, false, Array) #9 /homepages/31/d841462698/htdocs/clickandbuilds/AliMall/wp-content/themes/storefront/page.php(24): get_template_part('content', 'page') #10 /homepages/31/d841462698/htdocs/clickandbuilds/AliMall/wp-includes/template-loader.php(106): include('/homepages/31/d...') #11 /homepages/31/d841462698/htdocs/clickandbuilds/AliMall/wp-blog-header.php(19): require_once('/homepages/31/d...') #12 /homepages/31/d841462698/htdocs/clickandbuilds/AliMall/index.php(17): require('/homepages/31/d...') #13 {main} thrown in /homepages/31/d841462698/htdocs/clickandbuilds/AliMall/wp-content/plugins/groupby-for-woocommerce/public/class-wc-groupbuy-public.php on line 828