Nested sorting reliably breaks

[assertchris]

I'm experimenting with nested sorting, and it appears to break pretty reliably: https://codepen.io/assertchris/pen/OJKrzqB?editors=1000

Try to drag one of the 2 items into the nesting container that appears as you drag. When you drag it out, you get a nextSibling JS error (which I suspect is because the list is now empty, but I haven't been able to confirm this).

[ekwoka]

Likely fixed in #4361

[imade-nl]

I ran into the same problem. Latest version.