Extension Help with getting parent element

my code:

function changeamount() {
  var shown1;
  var parentnodeofshown1;
  var span = document.getElementById('nav-robux-amount')
  span.textContent = "500"
  var clickbutton1 = document.getElementsByClassName('btn-navigation-nav-robux-md')
  var clickbutton = clickbutton1[0]
  clickbutton.onclick = function()  {
    shown1 = document.getElementById('nav-robux-balance')
    parentnodeofshown1 = shown1.parentNode
    parentnodeofshown1.removeChild(shown1)
    const newelement = document.createElement("a")
    newelement.href = "https://web.roblox.com/transactions"
    newelement.className = "rbx-menu-item"
    newelement.id = "nav-robux-balance"
    parentnodeofshown1.appendChild(newelement)
  }
}
setTimeout(changeamount,95);

btw this is being used on web.roblox.com

What is going wrong here?