firstWhereOrNull method
Implementation
T? firstWhereOrNull(bool Function(T) test) {
  try {
    return firstWhere(test);
  } on StateError {
    return null;
  }
}T? firstWhereOrNull(bool Function(T) test) {
  try {
    return firstWhere(test);
  } on StateError {
    return null;
  }
}