message: Whitespace toggle: Only remove extra copy if it exists
diff: @@ -35,5 +35,8 @@ export default function () {
  );
  // Make space for the new button by removing "Changes from" #655
  - select('[data-hotkey="c"]').firstChild.remove();
  + const uselessCopy = select('[data-hotkey="c"]');
  + if (uselessCopy) {
  + uselessCopy.firstChild.remove();
  + }
  }
  