════════ Exception caught by animation library ═════════════════════════════════ The Scrollbar's ScrollController has no ScrollPosition attached.

[captainJackSaprrowTolle]

6.4 滚动监听及控制 6.4.1 ScrollController 2. 实例

       @override
        Widget build(BuildContext context) {
          return Scaffold(
            appBar: AppBar(title: Text("滚动控制")),
            body: Scrollbar(
              child: ListView.builder(
                itemCount: 100,
                itemExtent: 50.0, //列表项高度固定时，显式指定高度是一个好习惯(性能消耗小)
                controller: _controller,
                itemBuilder: (context, index) {
                  return ListTile(title: Text("$index"),);
                }
              ),
            ),

Scrollbar里没有绑定controller: _controller 导致异常抛出