function push(list, items) {
  if (list.length > 0) {
    splice(list, list.length, 0, items)
    return list
  }

  return items
}
Append `items` (an array) at the end of `list` (another array).
When `list` was empty, returns `items` instead.

This prevents a potentially expensive operation when `list` is empty,
and adds items in batches to prevent V8 from hanging.

@template {unknown} T
  Item type.
@param {Array<T>} list
  List to operate on.
@param {Array<T>} items
  Items to add to `list`.
@returns {Array<T>}
  Either `list` or `items`.