Fatal error: Declaration of Xms\XmsAssetmanager\Domain\Repository\AssetItemRepository::findByIdentifier(string $identifier): ?Xms\XmsAssetmanager\Domain\Dto\AssetItem must be compatible with TYPO3\CMS\Extbase\Persistence\Repository::findByIdentifier($identifier) in /srv/www/t3web_v12/packages/xms_assetmanager/Classes/Domain/Repository/AssetItemRepository.php on line 162