removes null safety for now

example/lib/main.dart

@@ -23,16 +23,16 @@ class MyApp extends StatelessWidget {
 }
 
 class MyHomePage extends StatefulWidget {
-  MyHomePage({Key? key}) : super(key: key);
+  MyHomePage({Key key}) : super(key: key);
 
   @override
   _MyHomePageState createState() => _MyHomePageState();
 }
 
 class FakeTerminalBackend implements TerminalBackend {
-  late Completer<int> _exitCodeCompleter;
+  Completer<int> _exitCodeCompleter;
   // ignore: close_sinks
-  late StreamController<String> _outStream;
+  StreamController<String> _outStream;
 
   FakeTerminalBackend();
 
@@ -79,7 +79,7 @@ class FakeTerminalBackend implements TerminalBackend {
 }
 
 class _MyHomePageState extends State<MyHomePage> {
-  late TerminalIsolate terminal;
+  TerminalIsolate terminal;
 
   @override
   void initState() {