Error: A value of type 'int' can't be assigned to a parameter of type 'FutureOr<int>'.

main.dart

import 'dart:async';

class A {
  final FutureOr<int> a;
  
  const A({this.a: 2});
}

void main() async {
  final b = const A(); // Here we have an error;
  ///But in this case it works well
  //final b = new A();
  
  print(b.a);
}