fix(nitro): promisify proxy handler (#398)

src/server/dev.ts

@@ -1,10 +1,11 @@
 import { Worker } from 'worker_threads'
 
+import { IncomingMessage, ServerResponse } from 'http'
 import { loading as loadingTemplate } from '@nuxt/design'
 import chokidar, { FSWatcher } from 'chokidar'
 import debounce from 'debounce'
 import { stat } from 'fs-extra'
-import { createApp, Middleware, useBase } from 'h3'
+import { promisifyHandle, createApp, Middleware, useBase } from 'h3'
 import { createProxy } from 'http-proxy'
 import { listen, Listener, ListenOptions } from 'listhen'
 import servePlaceholder from 'serve-placeholder'
@@ -72,16 +73,17 @@ export function createDevServer (nitroContext: NitroContext) {
 
   // SSR Proxy
   const proxy = createProxy()
+  const proxyHandle = promisifyHandle((req: IncomingMessage, res: ServerResponse) => proxy.web(req, res, { target: workerAddress }, (_err: unknown) => {
+    // console.error('[proxy]', err)
+  }))
   app.use((req, res) => {
     if (workerAddress) {
       // Workaround to pass legacy req.spa to proxy
       // @ts-ignore
       if (req.spa) {
         req.headers['x-nuxt-no-ssr'] = 'true'
       }
-      proxy.web(req, res, { target: workerAddress }, (_err: unknown) => {
-        // console.error('[proxy]', err)
-      })
+      return proxyHandle(req, res)
     } else {
       res.setHeader('Content-Type', 'text/html; charset=UTF-8')
       res.end(loadingTemplate({}))