got the extra children to go away

packages/svelte/src/compiler/phases/2-analyze/visitors/AwaitBlock.js

@@ -41,9 +41,12 @@ export function AwaitBlock(node, context) {
 
 	mark_subtree_dynamic(context.path);
 
-	// this one doesn't get the new state because it still hoists to the existing scope
 	context.visit(node.expression, { ...context.state, expression: node.metadata.expression });
 
+	if (node.metadata.expression.has_await && context.state.fragment) {
+		context.state.fragment.metadata.is_async = true;
+	}
+
 	if (node.pending) context.visit(node.pending);
 	if (node.then) context.visit(node.then);
 	if (node.catch) context.visit(node.catch);

packages/svelte/src/compiler/phases/2-analyze/visitors/AwaitExpression.js

@@ -18,11 +18,11 @@ export function AwaitExpression(node, context) {
 		}
 
 		if (context.state.fragment) {
-			const len = context.state.fragment.metadata.hoisted_promises.promises.push(node.argument);
+			// const len = context.state.fragment.metadata.hoisted_promises.promises.push(node.argument);
-			context.state.analysis.hoisted_promises.set(
+			// context.state.analysis.hoisted_promises.set(
-				node.argument,
+			// 	node.argument,
-				b.member(context.state.fragment.metadata.hoisted_promises.id, b.literal(len - 1), true)
+			// 	b.member(context.state.fragment.metadata.hoisted_promises.id, b.literal(len - 1), true)
-			);
+			// );
 		}
 
 		suspend = true;

packages/svelte/src/compiler/phases/2-analyze/visitors/EachBlock.js

@@ -35,6 +35,11 @@ export function EachBlock(node, context) {
 		scope: /** @type {Scope} */ (context.state.scope.parent)
 	});
 
+	// TODO it should be impossible to be in the template and not have a fragment...
+	if (node.metadata.expression.has_await && context.state.fragment) {
+		context.state.fragment.metadata.is_async = true;
+	}
+
 	context.visit(node.body);
 	if (node.key) context.visit(node.key);
 	if (node.fallback) {

packages/svelte/src/compiler/phases/2-analyze/visitors/Fragment.js

@@ -12,7 +12,7 @@ export function Fragment(node, context) {
 	// a child fragment), which is necessary for ensuring that a `SnippetBlock` creates an
 	// async function in SSR. It feels like this is probably duplicative, but it's late
 	// and it works, so for now I'm doing it like this
-	node.metadata.is_async = node.metadata.hoisted_promises.promises.length > 0;
+	node.metadata.is_async ||= node.metadata.hoisted_promises.promises.length > 0;
 
 	if (node.metadata.hoisted_promises.promises.length === 1) {
 		// if there's only one promise in this fragment, we don't need to de-waterfall it

packages/svelte/src/compiler/phases/2-analyze/visitors/IfBlock.js

@@ -22,6 +22,10 @@ export function IfBlock(node, context) {
 		expression: node.metadata.expression
 	});
 
+	if (node.metadata.expression.has_await && context.state.fragment) {
+		context.state.fragment.metadata.is_async = true;
+	}
+
 	context.visit(node.consequent);
 	if (node.alternate) {
 		context.visit(node.alternate);

packages/svelte/src/internal/server/payload.js

@@ -32,7 +32,7 @@ export class Payload {
 	type;
 
 	/** @type {Payload | undefined} */
-	parent;
+	#parent;
 
 	/**
 	 * Asynchronous work associated with this payload. `initial` is the promise from the function
@@ -69,7 +69,7 @@ export class Payload {
 	constructor(global, local = { select_value: undefined }, parent, type) {
 		this.global = global;
 		this.local = { ...local };
-		this.parent = parent;
+		this.#parent = parent;
 		this.type = type ?? parent?.type ?? 'body';
 	}
 
@@ -108,6 +108,10 @@ export class Payload {
 	 */
 	push(content) {
 		if (typeof content === 'function') {
+			if (this.global.mode === 'sync') {
+				// TODO more-proper error
+				throw new Error('Encountered an asynchronous component while rendering synchronously');
+			}
 			this.#out.push(content());
 		} else {
 			this.#out.push(content);
@@ -148,7 +152,7 @@ export class Payload {
 	 * @returns {number[]}
 	 */
 	get_path() {
-		return this.parent ? [...this.parent.get_path(), this.parent.#out.indexOf(this)] : [];
+		return this.#parent ? [...this.#parent.get_path(), this.#parent.#out.indexOf(this)] : [];
 	}
 
 	/**
@@ -170,7 +174,7 @@ export class Payload {
 	}
 
 	copy() {
-		const copy = new Payload(this.global, this.local, this.parent, this.type);
+		const copy = new Payload(this.global, this.local, this.#parent, this.type);
 		copy.#out = this.#out.map((item) => (item instanceof Payload ? item.copy() : item));
 		copy.promises = this.promises;
 		return copy;

packages/svelte/tests/snapshot/samples/async-each-fallback-hoisting/_expected/server/index.svelte.js

@@ -10,18 +10,13 @@ export default function Async_each_fallback_hoisting($$payload) {
 			for (let $$index = 0, $$length = each_array.length; $$index < $$length; $$index++) {
 				let item = each_array[$$index];
 
-				$$payload.child(async ($$payload) => {
 				$$payload.push(`<!---->`);
 				$$payload.push(async () => $.escape(await Promise.reject('This should never be reached')));
-				});
 			}
 		} else {
 			$$payload.push('<!--[!-->');
-
-			$$payload.child(async ($$payload) => {
 			$$payload.push(`<!---->`);
 			$$payload.push(async () => $.escape(await Promise.resolve(4)));
-			});
 		}
 
 		$$payload.push(`<!--]-->`);

packages/svelte/tests/snapshot/samples/async-each-hoisting/_expected/server/index.svelte.js

@@ -13,10 +13,8 @@ export default function Async_each_hoisting($$payload) {
 		for (let $$index = 0, $$length = each_array.length; $$index < $$length; $$index++) {
 			let item = each_array[$$index];
 
-			$$payload.child(async ($$payload) => {
 			$$payload.push(`<!---->`);
 			$$payload.push(async () => $.escape(await item));
-			});
 		}
 
 		$$payload.push(`<!--]-->`);

packages/svelte/tests/snapshot/samples/async-if-alternate-hoisting/_expected/server/index.svelte.js

@@ -4,16 +4,10 @@ export default function Async_if_alternate_hoisting($$payload) {
 	$$payload.child(async ($$payload) => {
 		if (await Promise.resolve(false)) {
 			$$payload.push('<!--[-->');
-
-			$$payload.child(async ($$payload) => {
 			$$payload.push(async () => $.escape(await Promise.reject('no no no')));
-			});
 		} else {
 			$$payload.push('<!--[!-->');
-
-			$$payload.child(async ($$payload) => {
 			$$payload.push(async () => $.escape(await Promise.resolve('yes yes yes')));
-			});
 		}
 
 		$$payload.push(`<!--]-->`);

packages/svelte/tests/snapshot/samples/async-if-hoisting/_expected/server/index.svelte.js

@@ -4,16 +4,10 @@ export default function Async_if_hoisting($$payload) {
 	$$payload.child(async ($$payload) => {
 		if (await Promise.resolve(true)) {
 			$$payload.push('<!--[-->');
-
-			$$payload.child(async ($$payload) => {
 			$$payload.push(async () => $.escape(await Promise.resolve('yes yes yes')));
-			});
 		} else {
 			$$payload.push('<!--[!-->');
-
-			$$payload.child(async ($$payload) => {
 			$$payload.push(async () => $.escape(await Promise.reject('no no no')));
-			});
 		}
 
 		$$payload.push(`<!--]-->`);