fix

packages/svelte/src/compiler/phases/3-transform/server/transform-server.js

@@ -1006,7 +1006,7 @@ function serialize_inline_component(node, expression, context) {
 	if (node.type === 'SvelteComponent' || (node.type === 'Component' && node.metadata.dynamic)) {
 		context.state.template.push(block_open, statement, block_close);
 	} else {
-		context.state.template.push(statement);
+		context.state.template.push(statement, block_close);
 	}
 }
 

packages/svelte/src/compiler/phases/3-transform/utils.js

@@ -294,7 +294,7 @@ export function clean_nodes(
 
 	const is_anchored = (is_dynamic_text || is_text) && parent.type === 'Fragment';
 
-	return { hoisted, trimmed, is_standalone, is_anchored };
+	return { hoisted, trimmed, is_standalone: false, is_anchored };
 }
 
 /**

packages/svelte/src/internal/client/render.js

@@ -1,9 +1,20 @@
 import { DEV } from 'esm-env';
 import { clear_text_content, empty, init_operations } from './dom/operations.js';
-import { HYDRATION_ERROR, HYDRATION_START, PassiveDelegatedEvents } from '../../constants.js';
+import {
+	HYDRATION_END,
+	HYDRATION_ERROR,
+	HYDRATION_START,
+	PassiveDelegatedEvents
+} from '../../constants.js';
 import { flush_sync, push, pop, current_component_context } from './runtime.js';
 import { effect_root, branch } from './reactivity/effects.js';
-import { hydrate_next, hydrating, set_hydrate_node, set_hydrating } from './dom/hydration.js';
+import {
+	hydrate_next,
+	hydrate_node,
+	hydrating,
+	set_hydrate_node,
+	set_hydrating
+} from './dom/hydration.js';
 import { array_from } from './utils.js';
 import { handle_event_propagation } from './dom/elements/events.js';
 import { reset_head_anchor } from './dom/blocks/svelte-head.js';
@@ -150,6 +161,13 @@ export function hydrate(component, options) {
 
 			const instance = _mount(component, { ...options, anchor });
 
+			if (
+				hydrate_node.nodeType !== 8 ||
+				/** @type {Comment} */ (hydrate_node).data !== HYDRATION_END
+			) {
+				throw HYDRATION_ERROR;
+			}
+
 			// flush_sync will run this callback and then synchronously run any pending effects,
 			// which don't belong to the hydration phase anymore - therefore reset it here
 			set_hydrating(false);