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

<script>
	import { beforeUpdate } from 'svelte';

	export let foo;
	export let bar;

	beforeUpdate(() => {
		if (foo.x !== bar.x) {
			throw new Error('mismatch');
		}
	});
</script>

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