Common Flutter Error (missing required argument)

Question

I am new to flutter and I was trying to test some liblaries. But unfortunately when I run this code, I get error:

error mesage:

error G4A9793AD: The value 'null' can't be assigned to the parameter type 'Key' because 'Key' is not nullable.

error image url

...some code...
    Widget build(BuildContext context) {
        return MaterialApp(
          debugShowCheckedModeBanner: false,
          home: MainPage(title: 'Flutter Convex BottomBar Sample'),
        );
      }
    }
 
class MainPage extends StatefulWidget {
  MainPage({required Key key, required this.title}) : super(key: key);
...some code...

Answer 1

You can't pass a value of null to the key parameter because it's non-nullable (can't have null as value) to mark it as nullable you should add ?:

MainPage({required Key? key, required this.title}) : super(key: key);

Anyway I think that's not what you want because its also not allowed. Simply drop the required keyword or pass a valid key to it:

MainPage({Key key, required this.title}) : super(key: key);

Answer 2

Either remove the Key key variable from MainPage by deleting it,

OR just provide a key

home: MainPage(title: 'Flutter Convex BottomBar Sample',key : Key('homepage'),),