fastify-session -- Request handler called even when response.redirect() is called in preHandler

index.js

const fastify = require('fastify')();
const fastifyCookie = require('fastify-cookie');
const fastifySession = require('fastify-session');
const MemoryStore = require('memorystore')(fastifySession);
const ms = require('ms');

// region Plugins =============================================================
fastify.register(fastifyCookie);
fastify.register(fastifySession, {
    cookieName: 'id',
    secret: 'a secret with minimum length of 32 characters',
    sessionMaxAge: ms('15 minutes'),
    cookie: {
        maxAge: ms('15 minutes'),
        secure: false,
        httpOnly: false,
        sameSite: true
    },
    store: new MemoryStore({
        checkPeriod: ms('1 minute'),
        ttl: ms('15 minutes')
    })
});
// endregion Plugins ==========================================================

// region Routes ==============================================================
fastify.route({
    method: 'GET',
    path: '/',

    // With this hook, the handler is still called
    preHandler: async function(request, reply) {
        console.log('GET / -> preHandler()');
        reply.redirect('/login');
    },

    // With this hook, the handler is not called (as expected)
    // preHandler: function(request, reply, next) {
    //     console.log('GET / -> preHandler()');
    //     reply.redirect('/login');
    // },

    handler: function(request, reply) {
        console.log('GET / -> handler() !! This should never be shown !!');
        reply.send({ hello: 'world' });
    }
});

fastify.route({
    method: 'GET',
    path: '/login',
    handler: function(request, reply) {
        console.log('GET /login -> handler()');
        reply.send('Please log in');
    }
});
// endregion Routes ===========================================================

fastify.listen(3000, err => {
    if (err) throw err;
    const { port } = fastify.server.address();

    console.log(`server listening on port ${port}`);
});