How to solve Flutter FormatException: Unexpected character

Question

I found a case here I tried to change the API to local API but when I GET the data an error occurs as shown and this happens on every page, but when I try to use the live API it's normal, why is this, before it was normal just when you want to use a local API or a live API. Thank you in advance.

and this my code:

class Constant {
  // static const String baseURL = 'http://dev.api.app.asdsadsadasd.com/v1';
  static const String baseURL = 'http://192.168.1.115:8080/v1';
  static const String token = 'access_token';
}

and this api call:

class BiodataProvider extends ChangeNotifier {
  Future<UserBiodata> getBiodata() async {
    String url = Constant.baseURL;
    // String _token = await UtilSharedPreferences.getToken();
    //SharedPreferences _pref = await SharedPreferences.getInstance();
    String token = await UtilSharedPreferences.getToken();
    final response = await http.get(
      Uri.parse(
        '$url/auth/mhs_siakad/biodata',
      ),
      headers: {
        'Authorization': 'Bearer $token',
      },
    );

    print(response.statusCode);
    print(response.body);
    if (response.statusCode == 200) {
      return UserBiodata.fromJson(jsonDecode(response.body));
    } else {
      throw Exception('Token Expired!');
    }
  }
}

this call api in widget UI

FutureBuilder<UserBiodata>(
                future: biodataProvider.getBiodata(),
                builder: (context, snapshot) {
                  if (snapshot.hasData) {
                    // return Text(snapshot.data!.status);
                    return Column(
                      mainAxisAlignment: MainAxisAlignment.center,
                      children: [
                        Image.asset(
                          'assets/images/user_prof.png',
                          height: 65,
                        ),
                        const SizedBox(
                          height: 12,
                        ),
                        Text(
                          snapshot.data!.data.name.toString(),
                          style: bold15,
                        ),
                        const SizedBox(
                          height: 2,
                        ),
                        Text(
                          snapshot.data!.data.nim,
                          style: regular5,
                        ),
                        const SizedBox(
                          height: 2,
                        ),
                        Text(
                          snapshot.data!.data.prodi,
                          style: regular5,
                        ),
                        Text(
                          'IPK ${snapshot.data!.data.ipk}',
                          style: bold5,
                        ), ...