check runtime errors (#9791)

Co-authored-by: Rich Harris <rich.harris@vercel.com>

packages/svelte/tests/runtime-legacy/shared.ts

@@ -305,6 +305,11 @@ async function run_test_variant(
 						compileOptions
 					});
 				}
+
+				if (config.runtime_error && !unhandled_rejection) {
+					unintended_error = true;
+					assert.fail('Expected a runtime error');
+				}
 			} finally {
 				instance.$destroy();
 				assert_html_equal(

packages/svelte/tests/runtime-runes/samples/effect-infinite/_config.js

@@ -1,7 +0,0 @@
-import { test } from '../../test';
-
-export default test({
-	runtime_error:
-		'ERR_SVELTE_TOO_MANY_UPDATES: Maximum update depth exceeded. This can happen when a reactive block or effect repeatedly sets a new value. Svelte limits the number of nested updates to prevent infinite loops.',
-	async test({ assert, target }) {}
-});

packages/svelte/tests/runtime-runes/samples/effect-infinite/main.svelte

@@ -1,11 +0,0 @@
-<script>
-  const v = { value: 1 };
-  let s = $state(v)
-
-  $effect(() => {
-		s = v;
-		s;
-	});
-</script>
-
-{JSON.stringify(s)}