Issue #3233138: If necessary update drupal/core-composer-scaffold and drupal/core-project-message

src/Validator/UpdateVersionValidator.php

@@ -57,7 +57,8 @@ class UpdateVersionValidator implements EventSubscriberInterface {
    */
   public function checkUpdateVersion(PreStartEvent $event): void {
     $from_version = ExtensionVersion::createFromVersionString($this->getCoreVersion());
-    $core_package_name = $this->updater->getCorePackageName();
+    $core_package_names = $this->updater->getCorePackageNames();
+    $core_package_name = reset($core_package_names);
     $to_version = ExtensionVersion::createFromVersionString($event->getPackageVersions()[$core_package_name]);
 
     if ($from_version->getMajorVersion() !== $to_version->getMajorVersion()) {