From bbc64f951510c18708fd22917a7b71d60e315d29 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Tue, 5 Aug 2025 21:10:07 -0400
Subject: [PATCH] handle non-iterables

---
 packages/svelte/src/internal/client/reactivity/async.js | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/packages/svelte/src/internal/client/reactivity/async.js b/packages/svelte/src/internal/client/reactivity/async.js
index fb6bc15c84..def112f6d8 100644
--- a/packages/svelte/src/internal/client/reactivity/async.js
+++ b/packages/svelte/src/internal/client/reactivity/async.js
@@ -140,6 +140,10 @@ export async function* for_await_track_reactivity_loss(iterable) {
 	// @ts-ignore
 	const iterator = iterable[Symbol.asyncIterator]?.() ?? iterable[Symbol.iterator]?.();
 
+	if (iterator === undefined) {
+		throw new TypeError('value is not async iterable');
+	}
+
 	/** Whether the completion of the iterator was "normal", meaning it wasn't ended via `break` or a similar method */
 	let normal_completion = false;
 	try {