Main JS error

Uncaught TypeError: Cannot read properties of null (reading 'querySelector')

?

See screenshot below ??

?

edited code

const wrapper = document.querySelector("#ash-dragable-hook-panel");
if (wrapper) {
  const header = wrapper.querySelector(".ash-show-move-window");

  function onDrag({movementX, movementY}){
    let getStyle = window.getComputedStyle(wrapper);
    let leftVal = parseInt(getStyle.left);
    let topVal = parseInt(getStyle.top);
    wrapper.style.left = ${leftVal + movementX}px;
    wrapper.style.top = ${topVal + movementY}px;
  }

  header.addEventListener("mousedown", ()=>{
    header.classList.add("ash_active");
    header.addEventListener("mousemove", onDrag);
  });

  document.addEventListener("mouseup", ()=>{
    header.classList.remove("ash_active");
    header.removeEventListener("mousemove", onDrag);
  });
}