Flutter 主体可能正常完成，导致返回 'null'，但返回类型是潜在的不可空类型？

Question

我正在使用 flutter 从 API 返回数据，但我遇到问题告诉我

The body might complete normally, causing 'null' to be returned, but the
return type is a potentially non-nullable type.
Try adding either a return or a throw statement at the end.

这是我的方法:

Future<void> getDoctorsFromApi() async {
    List<int> ids = await findAllDoctor().then((list) {
      return list.map((e) => e.syncedId).toList();
    });
    doctors = await DoctorApi.getDoctors(ids).then((response) { // this is the line where error occurs
      if (response.statusCode == 200) {
        Iterable list = json.decode(response.body);
        return list.map((model) => Doctor.fromJson(model)).toList();
      } else {
        _showMyDialog();
      }
    });
    setState(() {
      insertDoctors(database!);
    });
  }

Answer 1

如果 response.statusCode 不是 200，doctors 的值是多少？处理那个通过创建可为 null 的局部变量:

final List<Doctor>? result = await DoctorApi.getDoctors(ids).then((response) {
  if (response.statusCode == 200) {
    Iterable list = json.decode(response.body);
    return list.map((model) => Doctor.fromJson(model)).toList();
  }
  return null;
});

if (result == null) {
  _showMyDialog();

} else {
  doctors = result;
  setState(() => insertDoctors(database!));
}