Test case without jqueryui: http://live.datatables.net/widoxiyu/1/edit
Test case with jqueryui: http://live.datatables.net/fezipuji/1
I copied the code from https://editor.datatables.net/examples/api/confirmClose. I'm seeing the error in a child row editor, but not sure that is relevant.
Note I couldn't get the styling working maybe because editor.jqueryui.min.css failed to load, but that is irrelevant.
If I edit a child row, change a field, then try to close the edit modal I see the confirmation message. If I cancel the confirmation message, the edit modal disappears even though I cancelled.
This seems to be related to jqueryui.