The function call is not returning null but still giving "null" to be returned error

I’m migrating my old version flutter code to latest version with null safety feature.

In a function call I am getting the error "The body might complete normally, causing ‘null’ to be returned, but the return type is a potentially non-nullable type". I have enclosed my code in try catch block and in catch block I added rethrow statement to prevent null exception.

This is my code.

    Future<Map<String, dynamic>> fetchTimeline(http.Client client) async {
        try {
          print('INVOICE URL: ${globals.ursl.getURL(URLS.GETINVOICEURL)}');

          Response response;
          Dio dio = new Dio();

          response = await dio.get(globals.ursl.getURL(URLS.GETINVOICEURL));
          print('INVOICE GET RESPONSE: $response');
          if (response.statusCode == 200) {
            Map mapobject = (json.decode(response.toString()));
            var succes = mapobject['success'];
            if (succes == 1) {
              if (mapobject['Invoice'][0]['address'] == null ||
                  mapobject['Invoice'][0]['address'] == '') {
                address = '';
              } else {
                address = mapobject['Invoice'][0]['address'];
              }

              if (mapobject['Invoice'][0]['contact'] == null ||
                  mapobject['Invoice'][0]['contact'] == '')
                phone = '';
              else
                phone = mapobject['Invoice'][0]['contact'];

              if (mapobject['Invoice'][0]['restaurant_name'] == null ||
                  mapobject['Invoice'][0]['restaurant_name'] == '') {
                name = ' ';
              } else {
                name = mapobject['Invoice'][0]['restaurant_name'];
              }
              logo = mapobject['Invoice'][0]['logo'];
              globals.invoiceData = mapobject['Invoice'][0];
              startTime();
              return mapobject['Invoice'][0];
            } else {
              return {};
            }
          }
        } catch (error) {
          client.close();

          print("CONNECTION CLOSED: $error");
          rethrow;
        }
      }

I have added rethrow in catch block but still error is there.
Anyone there to help me out.

Thanks

>Solution :

It’s a little hard to see with all the nested if statements, but you aren’t returning a Map<String, dynamic> in every branch. This condition if (response.statusCode == 200) { ... } does not have a corresponding else branch, and so if the statusCode is some value other than 200 you are not returning anything (which means you are implicitly returning null in that case).