Should send error response from a errorHandler without executing request lifecycle about fastify HOT 3 CLOSED

import Fastify from 'fastify';
const app = Fastify();

// 4. fallback to outer scoped and send
app.setErrorHandler(async (err, req, res) => {
  // You should send serialized content as last fallback.
  res.status(500).send(JSON.stringify({ msg: "error response" }));
  return res;
})

app.register((app, options, done)=>{
  // 1. enter route
  app.post('/', {handler: async (req, res) => {
    req.result = { msg: "hello"};
    res.status(200).send(req.result);
    return res;
  }})

  // 2. pre-serialize and throw
  app.addHook('preSerialization', async (req, res, payload) => {
    await asyncfunction();
    throw new Error('preSerialization error');
  });
  
  // 3. handle error and throw
  app.setErrorHandler(async (err, req, res) => {
    throw new Error('preSerialization error');
  });
  done();
});

const response = await app.inject({ method: 'POST', path: '/'})
console.log(response.body)