问错误颤振(186)]未处理异常: FormatException:意外字符(在字符1处)

EN

    void main() {
  HttpOverrides.global = new MyHttpOverrides();
  runApp(MaterialApp(
    home: login(),
  ));
}

class login extends StatefulWidget {
  @override
  _LoginState createState() => _LoginState();
}

class _LoginState extends State<login>{
  var email,password;
  final _key = new GlobalKey<FormState>();
  check(){
    final form = _key.currentState;
    if(form.validate()){
      form.save();
      login();
    }
  }

  login() async{
    final response = await http.post(Uri.parse("link"),
        body: {
      "email" : email,
      "password" : password
    });
    final data = jsonDecode(response.body);
    print(data);
  }

  bool _secureText = false;
  showHide(){
    setState(() {
      _secureText = !_secureText;
    });
  }