Blocked website after last update

After the last update of the plugin, the website (backend + frontend) does not load and the “critical error” message appears.
The details are:
Uncaught Error: Call to undefined method Composer\Autoload\ClassLoader::setClassMapAuthoritative() in […]/wp-content/plugins/wp-statistics/includes/vendor/composer/autoload_real.php:32

The page I need help with: [log in to see the link]