LSP signature requirement violation

main.dart

class Bird {
  void fly() {
    print('The bird is flying.');
  }
}

class Ostrich extends Bird {
  @override
  void fly() {
    throw UnsupportedError('Ostriches cannot fly.');
  }
}

void fly(Bird bird) {
  /// we expect there that we receive an object able to fly
  birf.fly();
}