a test config of a parent is not necessarily given 

typo3/ajax.php?ajaxID=tx_caretaker::nodeinfo&node=instance_2_test_11

PHP Warning: Illegal string offset 'overwritten_in' in /kunden/d-mind.de/webseiten/caretaker/typo3conf/ext/caretaker/classes/nodes/class.tx_caretaker_TestNode.php line 200