There's null issue in org.jsoup.select.Elements#set

[MicyToy]

the new org.jsoup.select.Elements#set(int, Element) method since 1.17.1 has an issue.

this call old.replaceWith(element) method, and this method calls parentNode.replaceChild(this, in). in the replaceChild method, out's parentNode is removed out.parentNode = null;. this may cause an null issue.

eg: a parent node has 5 child elements, if I replace the 3rd element twice, eg: first replace 1 with 3, and then replace 3 with 5, then will throw an exception.

org.jsoup.helper.ValidationException: Object must not be null
	at org.jsoup.nodes.Node.replaceWith(Node.java:512)
	at org.jsoup.select.Elements.set(Elements.java:703)
	at org.jsoup.select.Elements.set(Elements.java:30)

you also can test it with Collections.shuffle()

[MicyToy]

I've pushed a test case for this.
Issue 2212