Unhandled Exception: FormatException: Unexpected character (at character 1) Flutter connecting mysql - mysql

Question

I am getting this error in flutter when I am making my login page, I am sure that the server is returning JSON not HTML but I am still getting the error. I have even tried using some "test" links and I am getting the same error.
E/flutter (25538): [ERROR:flutter/lib/ui/ui_dart_state.cc(209)] Unhandled Exception: FormatException: Unexpected character (at character 1)
E/flutter (25538): <br />
E/flutter (25538): ^
E/flutter (25538):
This is my code
Future userLogin() async {
setState(() {
visible = true;
});
String email = emailController.text;
String password = passwordController.text;
var url = 'http://192.168.1.2/***************/*********.php';
var data = {'email': email, 'password': password};
var response = await http.post(Uri.parse(url), body: json.encode(data));
var message = jsonDecode(response.body);
if (message == 'Login Matched') {
// Hiding the CircularProgressIndicator.
setState(() {
visible = false;
});
Navigator.push(
context, MaterialPageRoute(builder: (context) => StageOne()));
} else {
setState(() {
visible = false;
});
showDialog(
context: context,
builder: (BuildContext context) {
return AlertDialog(
title: new Text(message),
actions: <Widget>[
FlatButton(
child: new Text("OK"),
onPressed: () {
Navigator.of(context).pop();
},
),
],
);
},
);
}
}