Fatal error: Uncaught Error: Class "Composer\Installer\LibraryInstaller" not found in /var/www/html1/wp-content/plugins/zettle-pos-integration/vendor/composer/installers/src/Composer/Installers/Installer.php:15 Stack trace: #0 {main} thrown in /var/www/html1/wp-content/plugins/zettle-pos-integration/vendor/composer/installers/src/Composer/Installers/Installer.php on line 15