fix: Webcontainer AsyncLocalStorage workaround throttle (#14526)

* don't reset `sync_store` and handle one request at a time

* dry Promise.withResolvers

* hardening webcontainer detection based on @webcontainer/env

* Revert "hardening webcontainer detection based on @webcontainer/env"

This reverts commit 0f5e744.

* changeset

* Update packages/kit/src/runtime/server/constants.js

Co-authored-by: Tee Ming <[email protected]>

* try this

* move current

---------

Co-authored-by: Rich Harris <[email protected]>
Co-authored-by: Tee Ming <[email protected]>
Co-authored-by: Rich Harris <[email protected]>

Author: 3 people

.changeset/deep-insects-do.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/kit': patch
+---
+
+fix: Webcontainer AsyncLocalStorage workaround

packages/kit/src/runtime/server/index.js

@@ -13,6 +13,9 @@ import { set_app } from './app.js';
 /** @type {Promise<any>} */
 let init_promise;
 
+/** @type {Promise<void> | null} */
+let current = null;
+
 export class Server {
 	/** @type {import('types').SSROptions} */
 	#options;
@@ -31,9 +34,6 @@ export class Server {
 		if (IN_WEBCONTAINER) {
 			const respond = this.respond.bind(this);
 
-			/** @type {Promise<void> | null} */
-			let current = null;
-
 			/** @type {typeof respond} */
 			this.respond = async (...args) => {
 				const { promise, resolve } = /** @type {PromiseWithResolvers<void>} */ (with_resolvers());