-
viewof val = html`<input type=range min=${-range} max=${range} value="${this ? this.value : null}">`
+
viewof val = {
  const slider = html`<input type=range min=${-viewof range.value} max=${viewof range.value} value="${this ? this.value : null}">`;
  function updateRange() {
    slider.min = -viewof range.value;
    slider.max = viewof range.value;
    slider.dispatchEvent(new CustomEvent('input'));
  }
  
  viewof range.addEventListener('input', updateRange);
  invalidation.then(() => {
    viewof range.removeEventListener('input', updateRange);
  });
  return slider;
}