MapController 无法在 location 的locationChanged方法里面调用

[zmGitHub]

Map 和 location 配合使用出现如下问题

// flutter 版本
Flutter 1.9.1+hotfix.5 • channel stable • https://github.com/flutter/flutter.git
Framework • revision 1aedbb1835 (11 天前) • 2019-10-17 08:37:27 -0700
Engine • revision b863200c37
Tools • Dart 2.5.0

// 插件版本 
amap_map_fluttify: ^0.2.4+9922976
amap_location_fluttify: ^0.2.3+9922976

.....
.....      
body: AmapView(
        onMapCreated: (controller) async {
          _controller = controller;
         // 如果此处用 await controller.setZoomLevel(18); 下面的代码都无效
          controller.setZoomLevel(18);
          await controller.setCenterCoordinate(36.10453694661458, 120.40822835286458);
          AmapLocation.startLocation(
            once: false,
            locationChanged: locationChanged: this._startLocation        
          ); 
.....
.....
  void _startLocation(Location location) async {
    double latitude = await location.latitude;
    double longitude = await location.longitude;
    print('***********');
    print("latitude: $latitude");
    print("longitude: $longitude");
   // 当前能改变经纬度 但是调用地图的 controller 是无效的
    await _controller?.setCenterCoordinate(36.10453694661458, 120.40822835286458);
  }