flutter - 颤振代码返回按下注销按钮时，在null上调用了方法'onDisconnect'

Question

下面的代码没有任何错误，但是按下注销按钮时无法注销。这是个人资料标签页代码。

这是代码

 class ProfileTabPage extends StatefulWidget {
  @override
  _ProfileTabPageState createState() => _ProfileTabPageState();
}

class _ProfileTabPageState extends State<ProfileTabPage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: Colors.black87,
      body: SafeArea(
          child: Column(
            mainAxisAlignment: MainAxisAlignment.center,
            children: [

              Text(driversInformation.name,
              style: TextStyle(fontSize: 65.0,
              color: Colors.white,
              fontWeight: FontWeight.bold),),

              Text(title + "driver",  style: TextStyle(fontSize: 20.0,
                  color: Colors.blueGrey[200], letterSpacing: 2.5,
                  fontWeight: FontWeight.bold),),

              SizedBox(height: 20.0, width: 200, child: Divider(color: Colors.white,),),

              SizedBox(height: 40.0,),

              InfoCard(
                text: driversInformation.phone,
                icon: Icons.phone,
                onPressed: () async {
                  print("this is phone.");
                },
              ),
              InfoCard(
                text: driversInformation.email,
                icon: Icons.email,
                onPressed: () async {
                print("this is email.");
                },),
              InfoCard(
                text: driversInformation.car_color + " " + driversInformation.car_model + " " + driversInformation.car_number,
                icon: Icons.car_repair,
                onPressed: () async {
                print("this is car info.");},),



              GestureDetector(
                onTap: (){
                  makeDriverOfflineNow();

                  FirebaseAuth.instance.signOut();
                  Navigator.pushNamedAndRemoveUntil(context, LoginScreen.idScreen, (route) => false);



                },
                child: Card(
                  color: Colors.red,
                  margin: EdgeInsets.symmetric(vertical: 20.0, horizontal: 110.0),
                  child: ListTile(
                    trailing: Icon(
                      Icons.follow_the_signs_outlined,
                      color: Colors.white,

                    ),

                    title: Text(getTranslated(context,"Sign out"),
                      textAlign: TextAlign.center,
                      style: TextStyle(
                        color: Colors.white,
                        fontSize: 16.0,

                      ),
                    ),
                  ),
                ),
              ),


            ],
          ),
    ),

    );

  }

  void makeDriverOfflineNow(){
    Geofire.removeLocation(currentfirebaseUser.uid);
    rideRequestRef.onDisconnect();
    rideRequestRef.remove();
    rideRequestRef= null;

  }
}

class InfoCard extends StatelessWidget
{

  final String text;
  final IconData icon;
  Function onPressed;

  InfoCard({this.text, this.icon, this.onPressed});

  @override
  Widget build(BuildContext context)
  {
    return GestureDetector(
      onTap: onPressed,
      child: Card(
        color: Colors.white,
        margin:EdgeInsets.symmetric(vertical: 10.0, horizontal: 25.0),
        child: ListTile(
          leading: Icon(
            icon,
            color: Colors.black87,
          ),
          title: Text(text, style: TextStyle(color: Colors.black87,
          fontSize: 16.0),),
        ),
      ),
    );
  }
}

this is the error message when pressing the signout button

======== 手势捕获的异常 ======================================= ========================= 处理手势时抛出以下 NoSuchMethodError：方法 'onDisconnect' 在 null 上被调用。接收方：null 尝试调用：onDisconnect()

抛出异常时，这是堆栈：#0 Object.noSuchMethod (dart:core-patch/object_patch.dart:54:5) #1 _ProfileTabPageState.makeDriverOfflineNow (package:driver_app/tabsPages/profileTabPage.dart:103:20 ) #2 _ProfileTabPageState.build。(package:driver_app/tabsPages/profileTabPage.dart:62:19) #3 GestureRecognizer.invokeCallback (package:flutter/src/gestures/recognizer.dart:182:24) #4 TapGestureRecognizer.handleTapUp (package:flutter/src/gestures /tap.dart:607:11) ... 处理程序：“onTap”识别器：TapGestureRecognizer#70f77 debugOwner：GestureDetector 状态：可能赢得竞技场 finalPosition：偏移（187.8，513.1） finalLocalPosition：偏移（187.8，43.6）按钮：1 发送轻按

标签： flutterdart