Issue #3437409 ForbidCoreChangesValidator.php

Closes #3437409

automatic_updates_extensions/src/Validator/ForbidCoreChangesValidator.php

@@ -47,7 +47,7 @@ final class ForbidCoreChangesValidator implements EventSubscriberInterface {
     $stage = $event->stage;
     // We only want to do this check if the stage belongs to Automatic Updates
     // Extensions.
-    if ($stage->getType() !== 'automatic_updates_extensions:attended') {
+    if ($stage->getType() !== 'automatic_updates_extensions:attended' || !$stage->stageDirectoryExists()) {
       return;
     }
     $active_core_packages = $this->getInstalledCorePackages($this->pathLocator->getProjectRoot());