reply 0 size with no error when using reply.send(stream) or reply.send(buffer)

[radiorz]

Prerequisites

• I have written a descriptive issue title
• I have searched existing issues to ensure the bug has not already been reported

Fastify version

4.0.0

Plugin version

4.0.0

Node.js version

16.17.1

Operating system

Windows

Operating system version (i.e. 20.04, 11.3, 10)

11

Description

reply stream and buffer get 0 size from route.

Steps to Reproduce

I use fastify-cli to build a brand new project.
and add route

fastify.get("/file", async function (request, reply) {
    const filePath = path.join(__dirname, "./aaa.txt");
    console.log(`filePath`, filePath);
    const fileStream = fs.createReadStream(filePath, "utf8");
    reply.header("Content-Type", "application/octet-stream");
    reply.send(fileStream);
  });
  fastify.get("/file1", async function (request, reply) {
    const filePath = path.join(__dirname, "./aaa.txt");
    console.log(`filePath`, filePath);
    fs.readFile(filePath, (err, fileBuffer) => {
      reply.send(err || fileBuffer);
    });
  });

to get it but reply 0 size file

Expected Behavior

reply the right file stream

[climba03003]

When using async-await, please return the reply object to signal fastify wait for your further response.

fastify.get("/file", async function (request, reply) {
    const filePath = path.join(__dirname, "./aaa.txt");
    console.log(`filePath`, filePath);
    const fileStream = fs.createReadStream(filePath, "utf8");
    reply.header("Content-Type", "application/octet-stream");
    return reply.send(fileStream);
});
fastify.get("/file1", async function (request, reply) {
  const filePath = path.join(__dirname, "./aaa.txt");
  console.log(`filePath`, filePath);
  fs.readFile(filePath, (err, fileBuffer) => {
    reply.send(err || fileBuffer);
  });
  return reply
});