[scrollable_positioned_list] Twitchy scroll animation

[subzero911]

This package gives some crazy scrolling animation (looks like a big number of items has been scrolled, but it's only a few):

bad.scroll.mp4

late final ItemScrollController _itemScrollController;

  @override
  void initState() {
    super.initState();
    _itemScrollController = ItemScrollController();
    WidgetsBinding.instance.addPostFrameCallback((_) {
      if (controller.mode == TaskScreenMode.edit) {
        unawaited(
          _itemScrollController.scrollTo(index: controller.icon.index, duration: 400.ms),
        );
      }
    });

ScrollablePositionedList.separated(
                                itemScrollController: _itemScrollController,
                                padding: horizontalPadding,
                                scrollDirection: Axis.horizontal,
                                itemBuilder: (_, index) { ... }

Compare it to the standard library ScrollController animation:

good.scroll.mp4

 _iconsSc = ScrollController();
    WidgetsBinding.instance.addPostFrameCallback((_) {
      if (controller.mode == TaskScreenMode.edit) {
        _iconsSc.animateTo(52.0 * controller.icon.index, duration: 400.ms, curve: Curves.linear);
      }
    });

                           ListView.separated(
                                controller: _iconsSc,
...