firstOrNull property
Gets the first (key,value) stored in the box
Implementation
Future<MapEntry<TKey, TVal>?> get firstOrNull async {
var firstOrDefaultKey = dataBox.keys.isEmpty ? null : dataBox.keys.first;
if (firstOrDefaultKey == null) return null;
final val = await dataBox.get(firstOrDefaultKey);
if (val == null) return null;
return MapEntry(firstOrDefaultKey, val);
}