HiveObject subclasses issue: must not register base class HiveObject

main.dart

import 'package:hive/hive.dart';

/////////////// 'vehicle.dart' ///////////////
@HiveType(typeId: 0)
class Vehicle extends HiveObject {
  @HiveField(0)
  String name;
}

@HiveType(typeId: 1)
class Car extends Vehicle {}

@HiveType(typeId: 2)
class Boat extends Vehicle {}

/////////////// 'main.dart' ///////////////
void main() async {
  Hive.init('./');
  // Hive.registerAdapter(VehicleAdapter()); // <== **if uncomment this line, won't work after box.close()**
  Hive.registerAdapter(CarAdapter());
  Hive.registerAdapter(BoatAdapter());
  
  print('Opening hive box named "test"');
  await Hive.openBox<Vehicle>('test');
  final box = Hive.box<Vehicle>('test');
  await box.clear();

  await box.add(Car());
  await box.add(Boat());
  await box.add(Car());
  await box.add(Boat());

  print('box values before box.close():');
  for (final v in box.values) {
    print(v);
  }
  await box.close();
  print('box closed!');

  /////////////
  await Hive.openBox<Vehicle>('test');
  final box2 = Hive.box<Vehicle>('test');

  print('box values after re-opening box:');
  for (final v in box2.values) {
    print(v);
  }
}

/////////////// 'vehicle.g.dart' ///////////////
class VehicleAdapter extends TypeAdapter<Vehicle> {
  @override
  final typeId = 0;

  @override
  Vehicle read(BinaryReader reader) {
    var numOfFields = reader.readByte();
    var fields = <int, dynamic>{
      for (var i = 0; i < numOfFields; i++) reader.readByte(): reader.read(),
    };
    return Vehicle()..name = fields[0] as String;
  }

  @override
  void write(BinaryWriter writer, Vehicle obj) {
    writer
      ..writeByte(1)
      ..writeByte(0)
      ..write(obj.name);
  }
}

class CarAdapter extends TypeAdapter<Car> {
  @override
  final typeId = 1;

  @override
  Car read(BinaryReader reader) {
    var numOfFields = reader.readByte();
    var fields = <int, dynamic>{
      for (var i = 0; i < numOfFields; i++) reader.readByte(): reader.read(),
    };
    return Car()..name = fields[0] as String;
  }

  @override
  void write(BinaryWriter writer, Car obj) {
    writer
      ..writeByte(1)
      ..writeByte(0)
      ..write(obj.name);
  }
}

class BoatAdapter extends TypeAdapter<Boat> {
  @override
  final typeId = 2;

  @override
  Boat read(BinaryReader reader) {
    var numOfFields = reader.readByte();
    var fields = <int, dynamic>{
      for (var i = 0; i < numOfFields; i++) reader.readByte(): reader.read(),
    };
    return Boat()..name = fields[0] as String;
  }

  @override
  void write(BinaryWriter writer, Boat obj) {
    writer
      ..writeByte(1)
      ..writeByte(0)
      ..write(obj.name);
  }
}