avoid_init_to_null

Redundant initialization to 'null'.

The analyzer produces this diagnostic when a nullable variable is explicitly initialized to null. The variable can be a local variable, field, or top-level variable.

A variable or field that isn't explicitly initialized automatically gets initialized to null. There's no concept of "uninitialized memory" in Dart.

The following code produces this diagnostic because the variable f is explicitly initialized to null:

class C {
  int? f = null;

  void m() {
    if (f != null) {
      print(f);
    }
  }
}

Remove the unnecessary initialization:

class C {
  int? f;

  void m() {
    if (f != null) {
      print(f);
    }
  }
}