getTodayWeather method Null safety

Implementation

static getTodayWeather(double x, double y) async {
  DateTimeFormat dateInfo = baseTime(DateTime.now());

  Map<String, String> parameter = {
    "serviceKey": decodingKey,
    "numOfRows": "300",
    "pageNo": "1",
    "base_date": dateInfo.date,
    "base_time": dateInfo.time,
    "nx": "55",
    "ny": "127",
    "dataType": "JSON",
  };

  String queryString = Uri(queryParameters: parameter).query;
  print("queryString: $queryString");
  String uri = endPoint + "?" + queryString;
  print("uri: $uri");
  Response response = await get(Uri.parse(uri));
  String bodyString = utf8.decode(response.bodyBytes);
  final Map<String, dynamic> data = await compute(_jsonDecode, bodyString);
  final Map<String, dynamic> res = data['response'];
  final Map<String, dynamic> body = res["body"];
  final Map<String, dynamic> items = body["items"];
  final List item = items["item"] as List;
  final List<Weather> list = item.map((e) => Weather.fromJSON(e)).toList();
  final Weather? tmp = list.where((element) => element.category == "TMP").first; // 1시간 기온
  final Weather? sky = list.where((element) => element.category == "SKY").first; // 하늘상태
  final Weather? tmn = list.where((element) => element.category == "TMN").first; // 일 최저기온
  final Weather? tmx = list.where((element) => element.category == "TMX").first; // 일 최고기온
  final Weather? pty = list.where((element) => element.category == "PTY").first; // 강수형태
  print("tmp: $tmp");
  print("sky: $sky");
  print("tmn: $tmn");
  print("tmx: $tmx");
  print("pty: $pty");
  print("weather: ${skyState(sky!.fcstValue, pty!.fcstValue)}, 현재기온: ${tmp?.fcstValue}, 최저기온: ${tmn?.fcstValue}, 최고기온: ${tmx?.fcstValue}");
}