updating record with typeORM transactions

I have quiz api in nestjs, i am using typeORM for saving data, I want to do following transaction:

1. create quiz in quiz table with title and auto generated Id and empty array of questions
2. for each question try to save question in data base with generated quiz_id and questions input
3. save quiz and commit transaction

I am trying to test it but it dosent work

this is my create quiz operation:

async createQuiz(createQuizInput: CreateQuizInput): Promise <Quiz>{
        const {title, questions} = createQuizInput;

        const queryRunner = this.dataSource.createQueryRunner();

        await queryRunner.connect();
        await queryRunner.startTransaction();

        try{
            let quiz = this.quizRepository.create({title});
            quiz = await queryRunner.manager.save(quiz)

            for(const question of questions){ 
                const questionsToSave = await this.questionService.createQuestion(quiz.id, question);
                await queryRunner.manager.save(questionsToSave)
                quiz.questions.push(questionsToSave)
            }

            await queryRunner.manager.save(quiz);

            await queryRunner.commitTransaction();
            return quiz;
        }
        catch(err){
            await queryRunner.rollbackTransaction();
            throw new Error(err)
        }
        finally{
            await queryRunner.release();
        }
    }

my quesions is: how to fix following bug:

{
  "errors": [
    {
      "message": "Error: QueryFailedError: insert or update on table "question" violates foreign key constraint "FK_4959a4225f25d923111e54c7cd2"",
      "locations": [
        {
          "line": 2,
          "column": 3
        }
      ],
      "path": [
        "createQuiz"
      ],
      "extensions": {
        "code": "INTERNAL_SERVER_ERROR",
        "stacktrace": [
          "Error: Error: QueryFailedError: insert or update on table "question" violates foreign key constraint "FK_4959a4225f25d923111e54c7cd2"",
          "    at QuizService.createQuiz