Fatal Error

After updating to version 1.2.4 we received the following error after the stripe green tick appears;

Fatal error: Call to undefined method Composer\Autoload\ClassLoader::setPsr4() in /wp-content/plugins/yith-woocommerce-stripe/vendor/composer/autoload_real.php on line 33

Any ideas what could be causing this?

https://wordpress.org/plugins/yith-woocommerce-stripe/