Add failing test

packages/svelte/tests/runtime-runes/samples/if-nested-template/_config.js

@@ -0,0 +1,16 @@
+import { flushSync } from 'svelte';
+import { test } from '../../test';
+
+export default test({
+	async test({ assert, target }) {
+		const [btn1, btn2] = target.querySelectorAll('button');
+		const [div] = target.querySelectorAll('div');
+
+		flushSync(() => btn1?.click());
+		assert.htmlEqual(div.innerHTML, '123');
+		assert.equal(div.inert, true);
+
+		flushSync(() => btn2?.click());
+		assert.htmlEqual(div.innerHTML, '123');
+	}
+});

packages/svelte/tests/runtime-runes/samples/if-nested-template/main.svelte

@@ -0,0 +1,19 @@
+<script>
+	let outer = $state(true);
+	let inner = $state(123);
+
+	function outro() {
+		return { duration: 100 };
+	}
+</script>
+
+{#if outer}
+	<div out:outro>
+		{#if inner}
+			{inner.toString()}
+		{/if}
+	</div>
+{/if}
+
+<button onclick={() => { outer = false; inner = undefined; }}>Set both to falsy</button>
+<button onclick={() => { outer = true }}>Set outer to truthy</button>