message: Fix console error in `sticky-sidebar`
diff: @@ -16,11 +16,12 @@ function updateStickiness(): void {
  }
  const onResize = debounce(updateStickiness, {wait: 100});
  +const observer = new ResizeObserver(onResize);
  function init(): void {
  observe(sidebarSelector, {
  add(sidebar) {
  - new ResizeObserver(onResize).observe(sidebar, {box: 'border-box'});
  + observer.observe(sidebar, {box: 'border-box'});
  }
  });
  window.addEventListener('resize', onResize);
  @@ -34,5 +35,8 @@ void features.add(__filebasename, {
  exclude: [
  pageDetect.isEmptyRepoRoot
  ],
  - init
  + init,
  + deinit: () => {
  + observer.disconnect();
  + }
  });
  