Fatal error: Uncaught Error: Class "Magento\Staging\Model\Preview\RequestSigner" not found in /var/www/magento/html/generated/code/Magento/Staging/Model/Preview/RequestSigner/Proxy.php:7 Stack trace: #0 {main} thrown in /var/www/magento/html/generated/code/Magento/Staging/Model/Preview/RequestSigner/Proxy.php on line 7