Flutter Unhandled Exception: Null check operator used on a null value - flutter

Question

I am getting the following error Unhandled Exception: Null check operator and I am not sure if it is something wrong in my code or the library I am using. I am trying to test the livequery of the parse_server_sdk used by back4app because I require sending and receiving images in Realtime. Here is the relevant code:
import 'dart:io';
import 'package:filepicker_windows/filepicker_windows.dart';
import 'package:flutter/material.dart';
import 'package:parse_server_sdk_flutter/parse_server_sdk.dart';
void main() async {
final keyApplicationId = 'EPARW6nRAAyp5uehoDE7rBEby4wtehcZf9EayykS';
final keyClientKey = 'fDaL2DjyC9YdwCwZ4RB5c5vhACROaMOO1EjjL4Zn';
final keyParseServerUrl = 'https://parseapi.back4app.com';
final LIVE_QUERY_URL = 'wss://samuraichat.b4a.io';
await Parse().initialize(keyApplicationId, keyParseServerUrl,
clientKey: keyClientKey,
autoSendSessionId: true,
liveQueryUrl: LIVE_QUERY_URL,
coreStore: CoreStoreMemoryImp());
final LiveQuery liveQuery = LiveQuery();
QueryBuilder<ParseObject> query =
QueryBuilder<ParseObject>(ParseObject('FirstClass'))
..whereEqualTo('chatId', 1);
Subscription subscription = await liveQuery.client.subscribe(query);
subscription.on(LiveQueryEvent.create, (value) {
print('*** CREATE ***: ${DateTime.now().toString()}\n $value ');
print((value as ParseObject).objectId);
print((value as ParseObject).get('message'));
});
runApp(MyApp());
}
Here is the error stack:
[ERROR:flutter/lib/ui/ui_dart_state.cc(199)] Unhandled Exception: Null check operator used on a null value
#0 MethodChannel.binaryMessenger (package:flutter/src/services/platform_channel.dart:142:86)
#1 MethodChannel._invokeMethod (package:flutter/src/services/platform_channel.dart:148:36)
#2 MethodChannel.invokeMethod (package:flutter/src/services/platform_channel.dart:331:12)
#3 MethodChannelConnectivity.checkConnectivity (package:connectivity_platform_interface/src/method_channel_connectivity.dart:41:29)
#4 Connectivity.checkConnectivity (package:connectivity/connectivity.dart:46:22)
#5 Parse.checkConnectivity (package:parse_server_sdk_flutter/parse_server_sdk.dart:106:34)
#6 new LiveQueryReconnectingController (package:parse_server_sdk/src/network/parse_live_query.dart:45:28)
#7 new LiveQueryClient._internal (package:parse_server_sdk/src/network/parse_live_query.dart:146:30)
#8 LiveQueryClient._getInstance (package:parse_server_sdk/src/network/parse_live_query.dart:153:35)
#9 new LiveQuery (package:parse_server_sdk/src/network/parse_live_query.dart:416:30)
#10 main (package:chat_app/main.dart:18:37)
<asynchronous suspension>
Thanks.

Answer 1

Try to clean your app cache:
flutter clean

Answer 2

This bug should be fixed with this PR.
You use the current nullsafety branch by overriding the dependency in your pubspec.yaml:
dependency_overrides:
parse_server_sdk_flutter:
git:
url: https://github.com/parse-community/Parse-SDK-Flutter.git
ref: nullsafety
path: packages/flutter
parse_server_sdk:
git:
url: https://github.com/parse-community/Parse-SDK-Flutter.git
ref: nullsafety
path: packages/dart