Flutter SWAPI snapshot data null - json

Question

I want to use the SWAPI API in my flutter project but the snapshot has no data (it's null). No key is needed and when I click on the website I get the json data.
I did everything like in this documentation https://docs.flutter.dev/cookbook/networking/background-parsing.
persons_page.dart:
import 'dart:convert';
import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:http/http.dart' as http;
import 'package:star_wars/models/persons.dart';
class PersonsPage extends StatefulWidget {
const PersonsPage({ Key? key }) : super(key: key);
#override
State<PersonsPage> createState() => _PersonsPageState();
}
class _PersonsPageState extends State<PersonsPage> {
Future<List<Persons>> fetchPersons(http.Client client) async {
final response = await client.get(Uri.parse('https://swapi.dev/api/people/1'));
return compute(parsePersons, response.body);
}
List<Persons> parsePersons(String responseBody) {
final parsed = jsonDecode(responseBody).cast<Map<String,dynamic>>();
return parsed.map<Persons>((json) => Persons.fromJson(json)).toList();
}
#override
Widget build(BuildContext context) {
return FutureBuilder<List<Persons>>(
future: fetchPersons(http.Client()),
builder: (context, snapshot) {
if (snapshot.hasError) {
print(snapshot.data);
return const Center(
child: Text("An error has occurred!"),
);
} else if (snapshot.hasData) {
return PersonsList(persons: snapshot.data!);
} else {
return const Center(
child: CircularProgressIndicator(),
);
}
},
);
}
}
class PersonsList extends StatelessWidget {
const PersonsList({ Key? key, required this.persons }) : super(key: key);
final List<Persons> persons;
#override
Widget build(BuildContext context) {
return ListView.builder(
itemCount: persons.length,
itemBuilder: (context, index) {
return Text("Got it");
},
);
}
}
persons.dart:
class Persons {
final String name;
final String height;
final String mass;
final String hairColor;
final String skinColor;
final String eyeColor;
final String birthYear;
final String gender;
final List films;
final List vehicles;
final List starships;
const Persons({
required this.name,
required this.height,
required this.mass,
required this.hairColor,
required this.skinColor,
required this.eyeColor,
required this.birthYear,
required this.gender,
required this.films,
required this.vehicles,
required this.starships,
});
factory Persons.fromJson(Map<String, dynamic> json) {
return Persons(
name: json['name'] as String,
height: json['height'] as String,
mass: json['mass'] as String,
hairColor: json['hair_color'] as String,
skinColor: json['skin_color'] as String,
eyeColor: json['eye_color'] as String,
birthYear: json['birth_year'] as String,
gender: json['gender'] as String,
films: json['films'] as List,
vehicles: json['vehicles'] as List,
starships: json['starships'] as List,
);
}
}
the console output is:
Reloaded 1 of 632 libraries in 474ms.
I/flutter ( 6328): null
i don't know what is wrong with the code :/