This is my Error

fastify.io.of('/webusers').on('connect', (socket) => {
               ^

TypeError: Cannot read properties of undefined (reading 'of')

this is what i have defined. If someone could help that would be great!

const config = require('./config.json')

const fastify = require('fastify')()
const fastifySession = require('@fastify/session')
const fastifyCookie = require('@fastify/cookie')
const helmet = require('fastify-helmet')
const mariadb = require('mariadb')
const axios = require('axios')
const querystring = require('querystring')

const pool = mariadb.createPool({ host: config.database.host, user: config.database.user, password: config.database.password, database: config.database.db, connectionLimit: 10 })