TYPO3 Core

With more than one element, inserted in an inline area (IRRE), I've got the following JavaScript-Error when I have enabled the useSortable ("useSortable => 1"):

An invalid or illegal string was specified" code: "12
typo3/contrib/prototype/prototype.js Line 2844
results = $A(root.querySelectorAll(e)).map(Element.extend);\n

Because of this error the JavaScript is stopped and so the values of other fields will stay empty and I cannot sort the inline elements.

With only one inserted element or with the disabled useSortable option I've got no error.
In earlier TYPO3 versions like 4.2.10 I've got no error, as well.

I hope this is only a small JavaScript error which can be easily fixed ...

(issue imported from #M12352)