The method 'map' was called on null. Receiver: null Tried calling: map<Answer>(Closure: (String) => Answer)

[aymanjr]

i'm new the flutter environment
i was watching a course
and this works for the guy and not for me
the code :

import 'package:flutter/material.dart';
import './question.dart';
import './Answer.dart';

void main() {
runApp(Myapp());
}

class Myapp extends StatefulWidget {
@OverRide
State createState() {
return _MyappState();
}
}

class _MyappState extends State {
var questionindex = 0;

void answerTheq() {
setState(() {
if (questionindex >= 2) {
questionindex = 0;
} else {
questionindex += 1;
print('hi answer ');
}
});
}

@OverRide
Widget build(BuildContext context) {
var questions = [
{
'question text': 'what's your fav color : ',
'answers': ['blue', 'green', 'red', 'yellow']
},
{
'question text': 'what's your fav animal : ',
'answers': ['cat', 'dog', 'lion', 'zebra']
},
{
'question text ': 'what's your fav team : ',
'answers': ['rca', 'wac', 'far', 'mat']
},
];

return MaterialApp(
  home: Scaffold(
      appBar: AppBar(
        title: Text('My app'),
        backgroundColor: Colors.blue,
      ),
      body: Column(
        children: [
          Question(questions[questionindex]['question text ']),
          ...(questions[questionindex]['answer'] as List<String>)
                  .map((answer) {
                return Answer(answerTheq, answer);
              })?.toList() ??
              []
        ],
      )),
);

}
}

import 'package:flutter/material.dart';

class Answer extends StatelessWidget {
final Function getthefucntiondata;
final String answertext;

Answer(this.getthefucntiondata, this.answertext);

@OverRide
Widget build(BuildContext context) {
return Container(
width: double.infinity,
child: RaisedButton(
color: Colors.blue,
child: Text(answertext),
onPressed: getthefucntiondata,
));
}
}