I have a SO in my quiz game. When i reference it in the inspector unity freezes. But when i dont, it works without loading the questions and throws nullreferenceexception error

Questions & Answers
1

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using System.Linq;
using TMPro;
using UnityEngine.SceneManagement;

public class QueManager : MonoBehaviour
{
#region Variables

private Data data = new Data();

[SerializeField] GameEvents events = null;

[SerializeField] Animator timerAnimtor = null;
[SerializeField] TextMeshProUGUI timerText = null;
[SerializeField] Color timerHalfWayOutColor = Color.yellow;
[SerializeField] Color timerAlmostOutColor = Color.red;
private Color timerDefaultColor = Color.white;

private List<AnswerData> PickedAnswers = new List<AnswerData>();
private List<int> FinishedQuestions = new List<int>();
private int currentQuestion = 0;


private int timerStateParaHash = 0;
private IEnumerator IE_WaitTillNextRound = null;
private IEnumerator IE_StartTimer = null;

private bool IsFinished
{
    get
    {
        return (FinishedQuestions.Count < data.Questions.Length) ? false : true;
    }
}

#endregion

#region Default Unity Methods
void OnEnable()
{
    events.UpdateQuestionAnswer += UpdateAnswers;
}

void OnDisable()
{
    **events.UpdateQuestionAnswer -= UpdateAnswers;** This is the troublesome part
}

void Awake()
{
    **events.CurrentFinalScore = 0;** This is the troublesome part
}

void Start ()
{
    events.StartupHighscore = PlayerPrefs.GetInt(GameUtility.SavePrefKey);

    timerDefaultColor = timerText.color;
    LoadData();

    timerStateParaHash = Animator.StringToHash("TimerState");

    var seed = UnityEngine.Random.Range(int.MinValue, int.MaxValue);
    UnityEngine.Random.InitState(seed);

    Display();
}
#endregion

Below is the scriptable object

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

[CreateAssetMenu(fileName = “GameEvents”, menuName = “Quiz/new GameEvents”)]
public class GameEvents : ScriptableObject
{
public delegate void UpdateQuestionUICallback(Question question);
public UpdateQuestionUICallback UpdateQuestionUI;

public delegate void UpdateQuestionAnswerCallback(AnswerData pickedAnswer);
public UpdateQuestionAnswerCallback UpdateQuestionAnswer;

public delegate void DisplayResolutionScreenCallback(UIManager.ResolutionScreenType type, int score);
public DisplayResolutionScreenCallback DisplayResolutionScreen;

public delegate void ScoreUpdateCallback();
public ScoreUpdateCallback ScoreUpdated;

[HideInInspector]
public int CurrentFinalScore;

[HideInInspector]
public int StartupHighscore;

}

2

Thank you very much @oscarAbraham. below is the code where the delegates were created:

using System.Collections; 
using System.Collections.Generic; 
using UnityEngine;

[CreateAssetMenu(fileName = "GameEvents", menuName = "Quiz/new GameEvents")] 

public class GameEvents : ScriptableObject { 

public delegate void UpdateQuestionUICallback(Question question); 
public UpdateQuestionUICallback UpdateQuestionUI;

public delegate void UpdateQuestionAnswerCallback(AnswerData pickedAnswer); 
public UpdateQuestionAnswerCallback UpdateQuestionAnswer;

public delegate void DisplayResolutionScreenCallback(UIManager.ResolutionScreenType type, int score); 
public DisplayResolutionScreenCallback DisplayResolutionScreen;

public delegate void ScoreUpdateCallback(); 
public ScoreUpdateCallback ScoreUpdated;

[HideInInspector]
 public int CurrentFinalScore;
 [HideInInspector]
 public int StartupHighscore;

Here is where the problematic code is:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using System.Linq;
using TMPro;
using UnityEngine.SceneManagement;

public class QueManager : MonoBehaviour
{
    #region Variables
    
    private Data data = new Data();
    
    [SerializeField] GameEvents events = null;

    [SerializeField] Animator timerAnimtor = null;
    [SerializeField] TextMeshProUGUI timerText = null;
    [SerializeField] Color timerHalfWayOutColor = Color.yellow;
    [SerializeField] Color timerAlmostOutColor = Color.red;
    private Color timerDefaultColor = Color.white;

    private List<AnswerData> PickedAnswers = new List<AnswerData>();
    private List<int> FinishedQuestions = new List<int>();
    private int currentQuestion = 0;
    

    private int timerStateParaHash = 0;
    private IEnumerator IE_WaitTillNextRound = null;
    private IEnumerator IE_StartTimer = null;

    private bool IsFinished
    {
        get
        {
            return (FinishedQuestions.Count < data.Questions.Length) ? false : true;
        }
    }

    #endregion

    #region Default Unity Methods
    void OnEnable()
    {
        events.UpdateQuestionAnswer += UpdateAnswers;
    }

    void OnDisable()
    {
        events.UpdateQuestionAnswer -= UpdateAnswers; //This Line has Issues...
    }

    void Awake()
    {
        events.CurrentFinalScore = 0; //This Line has Issues...
    }

    void Start ()
    {
        events.StartupHighscore = PlayerPrefs.GetInt(GameUtility.SavePrefKey);

        timerDefaultColor = timerText.color;
        LoadData();

        timerStateParaHash = Animator.StringToHash("TimerState");

        var seed = UnityEngine.Random.Range(int.MinValue, int.MaxValue);
        UnityEngine.Random.InitState(seed);

        Display();
    }
    #endregion

    public void UpdateAnswers(AnswerData newAnswer)
    {
        if(data.Questions[currentQuestion].Type == AnswerType.Single)
        {
            foreach (var answer in PickedAnswers)
            {
                if(answer != newAnswer)
                {
                    answer.Reset();
                }
                PickedAnswers.Clear();
                PickedAnswers.Add(newAnswer);
            }
        }
        else
        {
            bool alreadyPicked = PickedAnswers.Exists(x => x == newAnswer);
            if(alreadyPicked)
            {
                PickedAnswers.Add(newAnswer);
            }
            else
            {
                PickedAnswers.Add(newAnswer);
            }
        }
    }

    public void EraseAnswers ()
    {
        PickedAnswers = new List<AnswerData>();
    }

    void Display()
    {
        EraseAnswers();
        var question = GetRandomQuestion();

        if (events.UpdateQuestionUI != null)
        {
            events.UpdateQuestionUI(question);
        }

        /*if(question.UseTimer)
        {
            UpdateTimer(question.UseTimer);
        }*/
    }

    public void Accept()
    {
        UpdateTimer(false);
        bool IsCorrect = CheckAnswers();
        FinishedQuestions.Add(currentQuestion);

        UpdateScore((IsCorrect) ? data.Questions[currentQuestion].AddScore : -data.Questions[currentQuestion].AddScore);

        if(IsFinished)
        {
            SetHighscore();
        }

        var type = (IsFinished) ? UIManager.ResolutionScreenType.Finish : (IsCorrect) ? UIManager.ResolutionScreenType.Correct : UIManager.ResolutionScreenType.Incorrect;

        if (events.DisplayResolutionScreen != null)
        {
            events.DisplayResolutionScreen(type, data.Questions[currentQuestion].AddScore);
        }
        if(type != UIManager.ResolutionScreenType.Finish){
            if (IE_WaitTillNextRound != null)
            {
                StopCoroutine(IE_WaitTillNextRound);
            }
            IE_WaitTillNextRound = WaitTillNextRound();
            StartCoroutine(IE_WaitTillNextRound);
        }
    }

    #region Timer Methods
    void UpdateTimer (bool state)
    {
        switch(state)
        {
            case true:
                IE_StartTimer = StartTimer();
                StartCoroutine(IE_StartTimer);

                timerAnimtor.SetInteger(timerStateParaHash, 2);
                break;
            case false:
                if(IE_StartTimer != null)
                {
                    StopCoroutine(IE_StartTimer);
                }

                timerAnimtor.SetInteger(timerStateParaHash, 1);
                break;
        }
    }

    IEnumerator StartTimer()
    {
        var totalTime = data.Questions[currentQuestion].Timer;
        var timeLeft = totalTime;

        timerText.color = timerDefaultColor;
        while(timeLeft > 0)
        {
            timeLeft--;

            if(timeLeft < totalTime / 2 && timeLeft > totalTime /4)
            {
                timerText.color = timerHalfWayOutColor;
            }
            if(timeLeft < totalTime / 4)
            {
                timerText.color = timerAlmostOutColor;
            }


            timerText.text = timeLeft.ToString();
            yield return new WaitForSeconds(1.0f);
        }
        Accept();
    }

    IEnumerator WaitTillNextRound()
    {
        yield return new WaitForSeconds(GameUtility.ResolutionDelayTime);
        Display();
    }
    #endregion

    /*Question GetRandomQuestion ()
    {
        var randomIndex = GetRandomQuestionIndex();
        currentQuestion = randomIndex;

        return data.Questions[currentQuestion];
    }

    int GetRandomQuestionIndex ()
    {
        var random = 0;
        if (FinishedQuestions.Count < data.Questions.Length)
        {
            do
            {
                random = UnityEngine.Random.Range(0, data.Questions.Length);
            }while (FinishedQuestions.Contains(random) || random == currentQuestion);
        }
        return random;
    }*/

    bool CheckAnswers()
    {
        if(!CompareAnswers())
        {
            return false;
        }
        return true;
    }

    bool CompareAnswers()
    {
        if(PickedAnswers.Count > 0)
        {
            List<int> c = data.Questions[currentQuestion].GetCorrectAnswers();
            List<int> p = PickedAnswers.Select(x => x.AnswerIndex).ToList();

            var f = c.Except(p).ToList();
            var s = p.Except(c).ToList();

            return !f.Any() && !s.Any();
        }
        return false;
    }
//Function called to load data(Questions)..
    void LoadData()
    {
       data = Data.Fetch();
    }

    public void RestartGame()
    {
        SceneManager.LoadScene(SceneManager.GetActiveScene().buildIndex);
    }

    public void QuitQuiz()
    {
        SceneManager.LoadScene("QuizHome");
    }

    private void SetHighscore()
    {
        var highscore = PlayerPrefs.GetInt(GameUtility.SavePrefKey);
        if(highscore < events.CurrentFinalScore)
        {
            PlayerPrefs.SetInt(GameUtility.SavePrefKey, events.CurrentFinalScore);
        }
    }

    private void UpdateScore(int add)
    {
        events.CurrentFinalScore += add;

        if(events.CurrentFinalScore < 0)
        {
            events.CurrentFinalScore = 0;
        }
        events.ScoreUpdated ?.Invoke();
    }

    #region  Getters

    Question GetRandomQuestion()
    {
        var randomIndex = GetRandomQuestionIndex();
        currentQuestion = randomIndex;

        return data.Questions[currentQuestion];
    }
    int GetRandomQuestionIndex()
    {
        var random = 0;
        if(FinishedQuestions.Count < data.Questions.Length)
        {
            do
            {
                random = UnityEngine.Random.Range(0, data.Questions.Length);
            }
            while(FinishedQuestions.Contains(random) || random == currentQuestion);
        }
        return random;
    }

    #endregion
}