Spread values (from ~cssx/tw etc.) are attribute dicts, not DOM nodes.
When they appear in non-element contexts (fragments, islands, lakes,
reactive branches), they must not be passed to appendChild/insertBefore.
Add _spread guard to platform domAppend and domInsertAfter — fixes
TypeError: Node.appendChild: Argument 1 does not implement interface Node.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
giles
9284a946ba