[BUGFIX] Fix crash with wrong blacklisting strings

Classes/Service/RegisterService.php

@@ -160,9 +160,11 @@ class RegisterService implements SingletonInterface {
 				$currentSiteBlacklist = GeneralUtility::trimExplode(',', $currentSite, TRUE);
 				if ((int) $currentSiteBlacklist[0] === $siteRootId) {
 					foreach ($currentSiteBlacklist as $excludedTemplate) {
-						[$extensionKey, $templateName] = GeneralUtility::trimExplode('.', $excludedTemplate);
-						if ($extensionKey && $templateName && isset($registerArray[$extensionKey][$templateName])) {
-							unset($registerArray[$extensionKey][$templateName]);
+						if (strpos($excludedTemplate, '.') !== FALSE) {
+							[$extensionKey, $templateName] = GeneralUtility::trimExplode('.', $excludedTemplate);
+							if ($extensionKey && $templateName && isset($registerArray[$extensionKey][$templateName])) {
+								unset($registerArray[$extensionKey][$templateName]);
+							}
 						}
 					}
 				}