使用fromJson时
无法将参数类型“String”分配给参数类型“Map〈String，dynamic〉”。

final fetchUserProvider = FutureProvider((ref) {
  const url = 'https://jsonplaceholder.typicode.com/users/1';
  return http
      .get(Uri.parse(url))
      .then((response) => UserModel.fromJson(response.body));//error 
});

class UserModel {
  final int id;
  final String name;
  final String username;

  const UserModel({
    required this.id,
    required this.name,
    required this.username,
  });

  static UserModel fromJson(Map<String, dynamic> json) {
    return UserModel(
      id: json['id'],
      name: json['name'],
      username: json['username'],
    );
  }

  @override
  String toString() => "$id, $name, $username";
}