fix: wrap component in boundary in `render`

packages/svelte/src/internal/client/custom-renderer/index.js

@@ -1,3 +1,4 @@
+import { boundary } from '../dom/blocks/boundary.js';
 import { branch, effect_root } from '../reactivity/effects.js';
 import { push_renderer } from './state.js';
 
@@ -50,10 +51,12 @@ export function createRenderer(renderer) {
 			const unmount = effect_root(() => {
 				var anchor = renderer.createComment('');
 				renderer.insert(target, anchor, null);
+				boundary(/** @type {*} */ (anchor), { pending: () => {} }, (anchor) => {
 					branch(() => {
 						Component(anchor, props);
 					});
 				});
+			});
 			cleanup();
 			return unmount;
 		}