HiveList<HiveObjectMixin>?' can't be assigned to a variable of type 'HiveList<HiveObjectMixin>

after build created database structure i get this error on `TABLE.g.dart` file:

error: A value of type 'HiveList?' can't be assigned to a variable of type 'HiveList'. (invalid_assignment at [XXXX] lib/database/user.g.dart:22)

for example:

```dart
return User()
..nameFamily = fields[0] as String
..mobileNumber = fields[1] as String
..address = (fields[2] as HiveList)?.castHiveList()
..wallet = (fields[3] as HiveList)?.castHiveList()
..transactions = (fields[4] as HiveList)?.castHiveList()
..categories = (fields[5] as HiveList)?.castHiveList()
..services = (fields[6] as HiveList)?.castHiveList();
```

removing `?` from `HiveList)?.castHiveList()` cause resolve this problem