open method Null safety
Opens the connection to the database and saves connection to db
Implementation
Future<void> open() async {
path = join(await _dbFactory.getDatabasesPath(), '$name.db');
final OpenDatabaseOptions options = OpenDatabaseOptions(
version: version,
onOpen: (_) => _ready.add(true),
);
db = await _dbFactory.openDatabase(path, options: options);
await loadTableSchema();
await _ready.stream.firstWhere((isReady) => isReady);
}