Fatal error: Uncaught Error: Class "Drupal\Core\Extension\ThemeExtensionList" not found in /home/qcsvlel/www/core/lib/Drupal/Core/Installer/InstallerThemeExtensionList.php:10 Stack trace: #0 {main} thrown in /home/qcsvlel/www/core/lib/Drupal/Core/Installer/InstallerThemeExtensionList.php on line 10