count method
Counts the records matching a category and tag filter.
Throws an AskarSessionException if the session is closed. Returns the count of matching records.
Implementation
Future<int> count({required String category, Map<String, dynamic>? tagFilter}) async {
  _throwOnNullHandle("Cannot count from closed session");
  try {
    final result = await askarSessionCount(handle!, category, tagFilter: tagFilter);
    return result.getValueOrException();
  } catch (e) {
    throw AskarSessionException('Error on session count: $e');
  }
}