NodeList.item() returns removed nodes

[qtow]

Example:

const doc = new DOMParser().parseFromString("<root><child/></root>", "text/xml")
const nodes = doc.getElementsByTagName("child");

// correct: { length: 1, item_0: "child" }
const first = {
    length: nodes.length,
    item_0: nodes.item(0)?.tagName ?? null,
};

doc.firstChild.removeChild(doc.firstChild.firstChild);

// should be: { length: 0, item_0: null}
// incorrect: { length: 0, item_0: "child" }
const second = {
    length: nodes.length,
    item_0: nodes.item(0)?.tagName ?? null,
};

console.log(first);
console.log(second);

Cause:
LiveNodeList is updated at dom.js:312 by copying all owned properties from an array. If the new array is shorter, indexes >= length are not removed.

Possible Solution:
Before or after copy(ls, list), explicitly delete the extra properties:

for (var i = ls.length; i in list; i += 1) {
    delete list[i];
}

Runtime & Version:
xmldom: 0.8.8
nodejs: 20.3.0

Additional context:
This causes problems with patterns like this:

for (let node; (node = nodes.item(0)) !== null; node.parentNode.removeChild(node)) {
    // ...
}

[karfau]

Thanks for the great bug report.
I would even suggest we should drop the property of part of the removeChild call using the delete keyword.
Your analysis was of course correct that the issue is in _updateLiveList.

[karfau]

The fix landed in 0.7 (lts), 0.8 (latest) and 0.9 (next)