Replacing an element with itself causes problems.

[jdngray77]

Obviously there's no practical use in replacing an element with itself, but robustness is in the edge cases.

Take the document:

body
| h1
| div

If we were to replace the h1 with itself via h1.replaceWith(h1), it's next sibling, in this case the div, would be deleted and the h1 would remain - but without a reference to it's parent.

In this state, the node traverser fails when rendering the tostring().

Minimal reproducable :

        val doc = Document("")

        val targetElement = Element("h1")
        doc.body().appendChild(targetElement)

        // During the replace, the target is removed from the children.
        // 'Ensure child list' within the replace operation is
        // different if there is no children, so we must add another child.
        //
        // Also, there must be children *after* the target element, else
        // there will be an index out of bounds during the replace operation.
        doc.body().appendChild(Element("div"))

        targetElement.replaceWith(targetElement)

        // The document can no longer be rendered to string.
        assertDoesNotThrow {
            println(doc)
        }

This can be solved with a simple equality check.

Self assigned, pr soon