Fetching the method 'findRenderObject' was called on null when showing in Dialog

[bipinvaylu]

Hey, I am facing following issue when trying to show feature introduction overlay using this library.

Code (inside _FriendsDetailsPageState):

void _showLikeFeatureIntroTutorial() {
    List<TutorialItens> tutorialItens = [];
    tutorialItens.add(TutorialItens(
      globalKey: keyMenu,
      touchScreen: true,
      top: 200,
      left: 200,
      shapeFocus: ShapeFocus.oval,
      children: [
        Text("Now you can like your friend's status tag by tapping on it"),
        SizedBox(
          height: 100,
        )
      ],
      widgetNext: Text("All done!"),
    ));

    Future.delayed(Duration(microseconds: 200)).then((value) {
      Tutorial.showTutorial(context, tutorialItens);
    });
  }

Using that widget in AlertDialog:

return showDialog<int>(
    context: context,
    barrierDismissible: true,
    builder: (BuildContext context) {
      return AlertDialog(
        backgroundColor: Theme.of(context).backgroundColor,
        contentPadding: EdgeInsets.all(20.0),
        shape: RoundedRectangleBorder(
            borderRadius: BorderRadius.all(Radius.circular(15.0))),
        content: FriendsDetailsPage(
          friendUser: friendUser,
          screenHeight: screenHeight,
          isLikeIntroFeatureShown: isLikeIntroFeatureShown,
        ),
      );
    },
  );

Runtime error log:

E/flutter (11422): [ERROR:flutter/lib/ui/ui_dart_state.cc(199)] Unhandled Exception: NoSuchMethodError: The method 'findRenderObject' was called on null.
E/flutter (11422): Receiver: null
E/flutter (11422): Tried calling: findRenderObject()
E/flutter (11422): #0      Object.noSuchMethod (dart:core-patch/object_patch.dart:63:5)
E/flutter (11422): #1      Tutorial._capturePositionWidget (package:tutorial/src/controller/tutorial_tutorial.dart:86:51)
E/flutter (11422): #2      Tutorial.showTutorial.<anonymous closure> (package:tutorial/src/controller/tutorial_tutorial.dart:15:20)
E/flutter (11422): #3      Tutorial.showTutorial.<anonymous closure> (package:tutorial/src/controller/tutorial_tutorial.dart:14:22)
E/flutter (11422): #4      List.forEach (dart:core-patch/growable_array.dart:403:8)
E/flutter (11422): #5      Tutorial.showTutorial (package:tutorial/src/controller/tutorial_tutorial.dart:14:14)
E/flutter (11422): #6      _FriendsDetailsPageState._showLikeFeatureIntroTutorial.<anonymous closure> (package:squadr/ui/home/friend/friend_detail_dialog.dart:313:16)
E/flutter (11422): #7      _rootRunUnary (dart:async/zone.dart:1436:47)
E/flutter (11422): #8      _CustomZone.runUnary (dart:async/zone.dart:1335:19)
E/flutter (11422): <asynchronous suspension>
E/flutter (11422): 
E/flutter (11422): [ERROR:flutter/lib/ui/ui_dart_state.cc(199)] Unhandled Exception: RangeError (index): Invalid value: Valid value range is empty: 0
E/flutter (11422): #0      List.[] (dart:core-patch/growable_array.dart:254:60)
E/flutter (11422): #1      Tutorial.showTutorial (package:tutorial/src/controller/tutorial_tutorial.dart:82:31)
E/flutter (11422): #2      _FriendsDetailsPageState._showLikeFeatureIntroTutorial.<anonymous closure> (package:squadr/ui/home/friend/friend_detail_dialog.dart:313:16)
E/flutter (11422): #3      _rootRunUnary (dart:async/zone.dart:1436:47)
E/flutter (11422): #4      _CustomZone.runUnary (dart:async/zone.dart:1335:19)
E/flutter (11422): <asynchronous suspension>
E/flutter (11422): 

Let me know if you need any other information.