Strange Dart 4

main.dart

class A {
  void f() {
    print('A.f called');
  }
}

class B implements A {
  void f({int test}); // optional non-nullable with no default value, also not a valid override

  // `f` above is not valid without a `noSuchMethod`
  noSuchMethod(Invocation invocation) {
    print('B.noSuchMethod');
  }
}

void main() {
  B().f(); // prints "B.noSuchMethod"
}