What is the eror this code

[Alpha69SL]

const hamburger = document.querySelector('.header .nav-bar .nav-list .hamburger');
const mobile_menu = document.querySelector('.header .nav-bar .nav-list ul');
const header = document.querySelector('.header .container');

hamburger.addEventListener('click',() => {
    hamburger.classList.toggle('active');
    mobile_menu.classList.toggle('active');
});

document.addEventListener('scroll', () => {
    var scroll_position = window.scrollY;
    if (scroll_position > 250) {
        header.style.backgroundColor = '#29323c';
    } else {
        header.style.backgroundColor = 'transparent';
    }
});