update examples/custom-server-fastify and replace depreaction (#38269)

## Bug

- [ ] Related issues linked using `fixes #number`
- [ ] Integration tests added
- [ ] Errors have helpful link attached, see `contributing.md`

## Feature

- [ ] Implements an existing feature request or RFC. Make sure the feature request has been accepted for implementation before opening a PR.
- [ ] Related issues linked using `fixes #number`
- [ ] Integration tests added
- [ ] Documentation added
- [ ] Telemetry added. In case of a feature if it's used or not.
- [ ] Errors have helpful link attached, see `contributing.md`

## Documentation / Examples

- [x] Make sure the linting passes by running `pnpm lint`
- [x] The examples guidelines are followed from [our contributing doc](https://github.com/vercel/next.js/blob/canary/contributing.md#adding-examples)


Co-authored-by: Balázs Orbán <18369201+balazsorban44@users.noreply.github.com>
Co-authored-by: JJ Kasper <22380829+ijjk@users.noreply.github.com>

examples/custom-server-fastify/package.json

@@ -6,10 +6,10 @@
     "start": "cross-env NODE_ENV=production node ./server.js"
   },
   "dependencies": {
-    "cross-env": "^7.0.2",
-    "fastify": "^3.19.1",
+    "cross-env": "^7.0.3",
+    "fastify": "^4.2.0",
     "next": "latest",
-    "react": "^17.0.2",
-    "react-dom": "^17.0.2"
+    "react": "^18.2.0",
+    "react-dom": "^18.2.0"
   }
 }

examples/custom-server-fastify/server.js

@@ -1,3 +1,4 @@
+/**  @type {import('fastify').FastifyInstance} */
 const fastify = require('fastify')({
   logger: { level: 'error' },
   pluginTimeout: 0,
@@ -16,32 +17,32 @@ fastify.register((fastify, opts, next) => {
       if (dev) {
         fastify.get('/_next/*', (req, reply) => {
           return handle(req.raw, reply.raw).then(() => {
-            reply.sent = true
+            reply.hijack()
           })
         })
       }
 
       fastify.get('/a', (req, reply) => {
         return app.render(req.raw, reply.raw, '/a', req.query).then(() => {
-          reply.sent = true
+          reply.hijack()
         })
       })
 
       fastify.get('/b', (req, reply) => {
         return app.render(req.raw, reply.raw, '/b', req.query).then(() => {
-          reply.sent = true
+          reply.hijack()
         })
       })
 
       fastify.all('/*', (req, reply) => {
         return handle(req.raw, reply.raw).then(() => {
-          reply.sent = true
+          reply.hijack()
         })
       })
 
       fastify.setNotFoundHandler((request, reply) => {
         return app.render404(request.raw, reply.raw).then(() => {
-          reply.sent = true
+          reply.hijack()
         })
       })
 
@@ -50,7 +51,7 @@ fastify.register((fastify, opts, next) => {
     .catch((err) => next(err))
 })
 
-fastify.listen(port, (err) => {
+fastify.listen({ port }, (err) => {
   if (err) throw err
   console.log(`> Ready on http://localhost:${port}`)
 })