fix test

packages/svelte/tests/runtime-runes/samples/error-boundary-20/_config.js

@@ -2,12 +2,14 @@ import { flushSync } from 'svelte';
 import { test } from '../../test';
 
 export default test({
-	test({ assert, target }) {
+	test({ assert, target, errors }) {
 		let btn = target.querySelector('button');
 
 		btn?.click();
 		flushSync();
 
+		assert.equal(errors.length, 1);
+
 		assert.htmlEqual(target.innerHTML, `<div class="error">An error occurred!</div>`);
 	}
 });