颤动拉动以滚动到位置刷新

Question

我正在尝试使用 ScrollablePositionedList 实现 pull to refresh。但得到错误。有没有办法同时实现。

        Expanded(child: RefreshIndicator(
              onRefresh: _pullToRefresh,
              child: ScrollablePositionedList.builder(
                physics: const AlwaysScrollableScrollPhysics(),
                scrollDirection: Axis.vertical,
                itemScrollController: _scrollController,
                padding: EdgeInsets.only(top: 8),
                itemCount: listTemp!= null ? listTemp.length : 0,
                itemBuilder: (BuildContext context, int index) {
                  if (index == listTemp.length - 1) {
                    height = 30;
                  } else {
                    height = 50;
                  }
                  return Container(
                    child: GestureDetector(
                      onTap: (){
                        print("Index:: $index");
                        _scrollController.scrollTo(index: index, duration: Duration(seconds: 1));
                      },
                      child: ListItem(
                        height: height,
                        list: listTemp,
                        index: index,
                        image: rImage,
                      ),
                    ),
                  );
                },
              ),
            ),
          )

错误：

Unhandled Exception: 'package:scrollable_positioned_list/src/scrollable_positioned_list.dart': Failed assertion: line 225 pos 12: '_scrollableListState != null': is not true.
    #0      _AssertionError._doThrowNew (dart:core-patch/errors_patch.dart:46:39)
    #1      _AssertionError._throwNew (dart:core-patch/errors_patch.dart:36:5)
    #2      ItemScrollController.scrollTo (package:scrollable_positioned_list/src/scrollable_positioned_list.dart:225:12)
    #3      _MyListPageState.goToCurrentDateIndex (package:flutter_app/pages/my_list_page.dart:306:29)
    #4      _MyListPageState._moveToCurrentTask.<anonymous closure> (package:flutter_app/pages/my_list_page.dart:293:19)
    #5      _rootRun (dart:async/zone.dart:1346:47)
    #6      _CustomZone.run (dart:async/zone.dart:1258:19)
    #7      _CustomZone.runGuarded (dart:async/zone.dart:1162:7)