Fix TypeError when morphing a text or comment node via outerHTML

[lizarusi]

Hi!

While using idiomorph at Walnut, we hit a bug that we've been carrying as a local patch — contributing the fix upstream.

The bug

Morphing a text or comment node with morphStyle: "outerHTML" throws:

TypeError: root.querySelectorAll is not a function
    at findIdElements (src/idiomorph.js:1088)
    at createIdMaps (src/idiomorph.js:1143)
    at createMorphContext (src/idiomorph.js:1003)
    at Object.morph (src/idiomorph.js:159)

Repro — e.g. replacing a comment placeholder with rendered content:

const parent = document.createElement("div");
parent.innerHTML = "<p>Before</p><!-- placeholder --><p>After</p>";
Idiomorph.morph(parent.childNodes[1], "<button>Bar</button>", {
  morphStyle: "outerHTML",
}); // 💥 TypeError: root.querySelectorAll is not a function

morph() passes the raw oldNode into createIdMaps → findIdElements, which calls root.querySelectorAll("[id]") — but text and comment nodes don't have querySelectorAll. We hit this in production at Walnut (morphing captured DOM that includes bare text/comment nodes) and have been carrying this fix as a local patch since 0.7.2.

The fix

Guard the call with optional chaining — the exact pattern this function already uses one line below for getAttribute ("root could be a document fragment which doesn't have getAttribute"). With the guard in place the rest of the algorithm handles non-element nodes correctly: the new tests show a text node and a comment node being morphed into the expected content, with siblings preserved.

First commit adds the failing tests, second commit makes them pass. npm run typecheck, npm run format:check, and the full suite pass, with coverage at 100%.