diff --git a/Classes/Utility/BackendUtility.php b/Classes/Utility/BackendUtility.php
--- a/Classes/Utility/BackendUtility.php
+++ b/Classes/Utility/BackendUtility.php	(date 1669401932377)
@@ -678,7 +678,7 @@
             }
         }
         // If current typeNum doesn't exist, set it to 0 (or to 1 for historical reasons, if 0 doesn't exist)
-        if (!isset($GLOBALS['TCA'][$table]['types'][$typeNum]) || !$GLOBALS['TCA'][$table]['types'][$typeNum]) {
+        if (is_array($typeNum) || !isset($GLOBALS['TCA'][$table]['types'][$typeNum]) || !$GLOBALS['TCA'][$table]['types'][$typeNum]) {
             $typeNum = isset($GLOBALS['TCA'][$table]['types']['0']) ? 0 : 1;
         }
         // Force to string. Necessary for eg '-1' to be recognized as a type value.