svelte/test/runtime/samples/set-in-onstate-dedupes-renders/Widget.html

<div>{{foo.x}}</div>

<script>
	export default {
		onstate({ current, changed }) {
			if (changed.foo || changed.bar) {
				if (current.foo.x !== current.bar.x) {
					throw new Error('mismatch');
				}
			}
		}
	};
</script>