From 7bbaedd6c749809ba987d937a57c6cd7c0fbd71b Mon Sep 17 00:00:00 2001
From: Dominic Gannaway <trueadm@users.noreply.github.com>
Date: Fri, 25 Oct 2024 20:38:25 +0100
Subject: [PATCH] fix: rethrow errors from await block if no catch block exists
 (#13819)

* chore: highlight swallowed errors from await blocks in DEV

* chore: highlight swallowed errors from await blocks in DEV

* chore: highlight swallowed errors from await blocks in DEV

* lint

* feedback

* feedback

* add test

* Update packages/svelte/tests/runtime-runes/samples/await-no-catch-error/main.svelte

---------

Co-authored-by: Simon H <5968653+dummdidumm@users.noreply.github.com>
---
 .changeset/blue-boats-call.md                 |  5 +++++
 .../src/internal/client/dom/blocks/await.js   |  4 ++++
 .../samples/await-no-catch-error/_config.js   | 22 +++++++++++++++++++
 .../samples/await-no-catch-error/main.svelte  | 10 +++++++++
 4 files changed, 41 insertions(+)
 create mode 100644 .changeset/blue-boats-call.md
 create mode 100644 packages/svelte/tests/runtime-runes/samples/await-no-catch-error/_config.js
 create mode 100644 packages/svelte/tests/runtime-runes/samples/await-no-catch-error/main.svelte

diff --git a/.changeset/blue-boats-call.md b/.changeset/blue-boats-call.md
new file mode 100644
index 0000000000..0f6c31025d
--- /dev/null
+++ b/.changeset/blue-boats-call.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: rethrow errors from await block if no catch block exists
diff --git a/packages/svelte/src/internal/client/dom/blocks/await.js b/packages/svelte/src/internal/client/dom/blocks/await.js
index 75bbb23cdd..3c6bc9900d 100644
--- a/packages/svelte/src/internal/client/dom/blocks/await.js
+++ b/packages/svelte/src/internal/client/dom/blocks/await.js
@@ -131,6 +131,10 @@ export function await_block(node, get_input, pending_fn, then_fn, catch_fn) {
 					// but let's use internal_set for consistency and just to be safe
 					internal_set(error_source, error);
 					update(CATCH, true);
+					if (!catch_fn) {
+						// Rethrow the error if no catch block exists
+						throw error_source.v;
+					}
 				}
 			);
 
diff --git a/packages/svelte/tests/runtime-runes/samples/await-no-catch-error/_config.js b/packages/svelte/tests/runtime-runes/samples/await-no-catch-error/_config.js
new file mode 100644
index 0000000000..568b58ff95
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/await-no-catch-error/_config.js
@@ -0,0 +1,22 @@
+import { flushSync } from 'svelte';
+import { test } from '../../test';
+
+export default test({
+	async test({ assert, target }) {
+		const b1 = target.querySelector('button');
+
+		let err = '';
+		window.addEventListener('error', (e) => {
+			e.preventDefault();
+			err = e.message;
+		});
+
+		b1?.click();
+		await Promise.resolve();
+		flushSync();
+
+		assert.throws(() => {
+			throw err;
+		}, /Test/);
+	}
+});
diff --git a/packages/svelte/tests/runtime-runes/samples/await-no-catch-error/main.svelte b/packages/svelte/tests/runtime-runes/samples/await-no-catch-error/main.svelte
new file mode 100644
index 0000000000..bd2fb1e2f2
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/await-no-catch-error/main.svelte
@@ -0,0 +1,10 @@
+<script>
+	const promise = Promise.reject('Test');
+	let toggle = $state(false);
+</script>
+
+<button onclick={() => toggle = !toggle}>toggle</button>
+
+{#if toggle}
+	{#await promise}{/await}
+{/if}