Exception thrown when using with GoogleMap

[takinok]

Describe the bug
When showing FlushBar and using 2 fingers on the Google Map(Especially rotate action), then the app throws an exception.
After this exception is thrown once, it also gets thrown when using any other gesture (one or two fingers).
It's may coursed by Flutter or Google Map. But, when using SnackBar, Exception is not thrown.

Device: Galaxy S20 5G
OS: Android 10
Baseband: SCG01KDU1ATI1
Kernel: 4.19.81-19596063
(Same exception doesn't happened on iPhone SE and 6S when I take same action/gesture)

Logs

E/flutter ( 8075): [ERROR:flutter/lib/ui/ui_dart_state.cc(177)] Unhandled Exception: Null check operator used on a null value
E/flutter ( 8075): #0      _AndroidMotionEventConverter.toAndroidMotionEvent (package:flutter/src/services/platform_views.dart:596:31)
E/flutter ( 8075): #1      AndroidViewController.dispatchPointerEvent (package:flutter/src/services/platform_views.dart:864:31)
E/flutter ( 8075): <asynchronous suspension>
E/flutter ( 8075): #2      _PlatformViewGestureRecognizer.handleEvent (package:flutter/src/rendering/platform_view.dart:535:26)
E/flutter ( 8075): #3      PointerRouter._dispatch (package:flutter/src/gestures/pointer_router.dart:77:12)
E/flutter ( 8075): #4      PointerRouter._dispatchEventToRoutes.<anonymous closure> (package:flutter/src/gestures/pointer_router.dart:122:9)
E/flutter ( 8075): #5      _LinkedHashMapMixin.forEach (dart:collection-patch/compact_hash.dart:377:8)
E/flutter ( 8075): #6      PointerRouter._dispatchEventToRoutes (package:flutter/src/gestures/pointer_router.dart:120:18)
E/flutter ( 8075): #7      PointerRouter.route (package:flutter/src/gestures/pointer_router.dart:106:7)
E/flutter ( 8075): #8      GestureBinding.handleEvent (package:flutter/src/gestures/binding.dart:358:19)
E/flutter ( 8075): #9      GestureBinding.dispatchEvent (package:flutter/src/gestures/binding.dart:338:22)
E/flutter ( 8075): #10     RendererBinding.dispatchEvent (package:flutter/src/rendering/binding.dart:267:11)
E/flutter ( 8075): #11     GestureBinding._handlePointerEvent (package:flutter/src/gestures/binding.dart:295:7)
E/flutter ( 8075): #12     GestureBinding._flushPointerEventQueue (package:flutter/src/gestures/binding.dart:240:7)
E/flutter ( 8075): #13     _rootRun (dart:async/zone.dart:1182:47)
E/flutter ( 8075): #14     _CustomZone.run (dart:async/zone.dart:1093:19)
E/flutter ( 8075): #15     _CustomZone.runGuarded (dart:async/zone.dart:997:7)
E/flutter ( 8075): #16     _CustomZone.bindCallbackGuarded.<anonymous closure> (dart:async/zone.dart:1037:23)
E/flutter ( 8075): #17     _rootRun (dart:async/zone.dart:1190:13)
E/flutter ( 8075): #18     _CustomZone.run (dart:async/zone.dart:1093:19)
E/flutter ( 8075): #19     _CustomZone.runGuarded (dart:async/zone.dart:997:7)
E/flutter ( 8075): #20     _CustomZone.bindCallbackGuarded.<anonymous closure> (dart:async/zone.dart:1037:23)
E/flutter ( 8075): #21     _microtaskLoop (dart:async/schedule_microtask.dart:41:21)
E/flutter ( 8075): #22     _startMicrotaskLoop (dart:async/schedule_microtask.dart:50:5)

Paste relevant code

Code

import 'dart:async';

import 'package:flutter/material.dart';
import 'package:google_maps_flutter/google_maps_flutter.dart';
import 'package:flushbar/flushbar.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Snackbar/Flushbar Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
        visualDensity: VisualDensity.adaptivePlatformDensity,
      ),
      home: MyHomePage(title: 'Snackbar/Flushbar Demo'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);
  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Map(),
    );
  }
}

class Map extends StatefulWidget {
  @override
  _MapState createState() => _MapState();
}

class _MapState extends State<Map> {
  Completer<GoogleMapController> _mapController = Completer();
  @override
  Widget build(BuildContext context) {
    return Container(
      child: Column(
        children: [
          Expanded(
            child: GoogleMap(
              onMapCreated: (GoogleMapController controller) {
                _mapController.complete(controller);
              },
              initialCameraPosition: CameraPosition(
                target: LatLng(35.65809922, 139.74135747),
                zoom: 15.0,
              ),
            ),
          ),
          Container(
            height: 50,
            child: Row(
              mainAxisAlignment: MainAxisAlignment.center,
              children: [
                RaisedButton(
                  onPressed: () {
                    final snackBar = SnackBar(
                      content: Text('お知らせ！'),
                      duration: Duration(seconds: 3),
                    );
                    Scaffold.of(context).showSnackBar(snackBar);
                  },
                  child: Text('SnackBar'),
                ),
                SizedBox(width: 50,),
                RaisedButton(
                    onPressed: () {
                      new Flushbar(
                        title: 'TITLE',
                        message: 'Test Message',
                        duration: Duration(seconds: 3),
                      )..show(context);
                    },
                    child: Text('FlushBar')),
              ],
            ),
          ),
        ],
      ),
    );
  }
}

Flutter doctor

D:\github\sample_gmap>flutter doctor
Doctor summary (to see all details, run flutter doctor -v):
[√] Flutter (Channel stable, 1.22.2, on Microsoft Windows [Version 10.0.18362.1139], locale ja-JP)
[√] Android toolchain - develop for Android devices (Android SDK version 30.0.1)
[√] Android Studio (version 3.6)
[√] VS Code (version 1.50.1)
[√] Connected device (1 available)