I'm created a simple React app and added a banner. But I'm getting a lot this error in Sentry from users.

Cannot read properties of null (reading 'getItem');

If someone knows what is a problem tell me please

setTimeout(() => {
  const banner = document.getElementById("banner");

  if (!window.localStorage?.getItem("seen")) {
    const button = document.getElementById("hide");

    if(button){
      button.addEventListener('click', () => {
      window.localStorage?.setItem("seen", 'true');
        banner.style.bottom = "-10vh";
        setTimeout(() => banner.remove(), 2000);
      });

      banner.style.removeProperty("visibility");
      setTimeout(() => banner.style.removeProperty("bottom"), 100);
    }
  } else banner?.remove();
}, 2000);