How can I fix LateInitializationError in Flutter when loading questions asynchronously?

Question

I have a LateInitializationError in Flutter and I dont know how to fix it. I am making a quiz app and requesting questions from an API. The error only shows up for half a second and afterwards the question loads in. I tried delaying the functions that come afterwards, but that didnt help.

The concrete Error Im getting is:

The following LateError was thrown building Quiz(dirty, state: _QuizState#74551):
LateInitializationError: Field 'currentQuestion' has not been initialized.

When the exception was thrown, this was the stack: 
#0      _QuizState.currentQuestion (package:demoapp/main.dart)
#1      _QuizState.build (package:demoapp/main.dart:267:21)

Heres the code:

class Quiz extends StatefulWidget {
  @override
  State<Quiz> createState() => _QuizState();
}

class _QuizState extends State<Quiz> {
  late Questions currentQuestion;
  late List<String> answers;
  List<bool?> answerValidation = [null, null, null, null];

  @override
  void initState() {
    asyncQuestion();
    super.initState();
  }

  void asyncQuestion() async{
    Questions currentQuestion1 = await loadQuestion();
    setState((){
      currentQuestion = currentQuestion1;
      answers = getRandomQuestionList(currentQuestion.wrongAnswers, currentQuestion.correctAnswer);
    });
  }

  validateAndShowQuestion(int userAnswerIndex) {
    int correctIndex = getCorrectAnswerIndex(currentQuestion.wrongAnswers, currentQuestion.correctAnswer);

    setState(() {
      if(userAnswerIndex == correctIndex) {
        answerValidation[correctIndex] = true;
        AssetsAudioPlayer audioPlayer = AssetsAudioPlayer();
        audioPlayer.open(
          Audio(
            'assets/correct-6033.mp3',
          ),
        );
      }
      else {
        answerValidation[userAnswerIndex] = false;
        AssetsAudioPlayer audioPlayer = AssetsAudioPlayer();
        audioPlayer.open(
          Audio(
            'assets/wrong-47985.mp3',
          ),
        );
      }

    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(),

      body: Center(
        child: Padding(
          padding: const EdgeInsets.all(8.0),
          child: Column(
            mainAxisAlignment: MainAxisAlignment.center,
            children: [
              const Spacer(),
              Text((currentQuestion.question), style: TextStyle(color: Colors.black, fontSize: 22, fontWeight: FontWeight.bold),
                textAlign: TextAlign.center,
              ),
              const Spacer(),
              GestureDetector(child: answerCard((answers[0]), context, answerValidation[0]),
                onTap: () {
                  validateAndShowQuestion(0);
                },),
              GestureDetector(child: answerCard((answers[1]), context, answerValidation[1]),
                onTap: () {
                  validateAndShowQuestion(1);
                },),
              GestureDetector(child: answerCard((answers[2]), context, answerValidation[2]),
                onTap: () {
                  validateAndShowQuestion(2);
                },),
              GestureDetector(child: answerCard((answers[3]), context, answerValidation[3]),
                onTap: () {
                  validateAndShowQuestion(3);
                },),
              const Spacer(),
            ]
          ),
        ),
      )
    );
  }
}

I would really appreciate any kind of help.

I tried delaying the function that comes next, but that didnt work. I also tried to change my variables to nullable variables. The problem with that method is, that the question and answers are being initialized with wrong values.

Answer 1

The problem lies in the following section: Text((currentQuestion.question). This code is located within the build method, which runs first. However, at that point, you have not assigned a value to the currentQuestion variable yet. To resolve this issue, please utilize a loader to wait until the data is loaded. By doing so, you will effectively address the problem.