错误＆＃39; NullReferenceException：对象引用未设置为对象的实例＆＃39;仅发生在Unity

Question

我目前正在开发2D平台游戏。每当切换按钮关闭时，以下脚本都应禁用音频。

using UnityEngine;
using System.Collections;
using System.Collections.Generic;
using UnityEngine.UI;
using System.IO;

public class SettingsManager : MonoBehaviour {

    // Use this for initialization
    public Toggle audioEnabled;
    public Button applyButton;
    public GameSettings gameSettings;

    void OnEnable()
    {
        gameSettings = new GameSettings();
        audioEnabled.onValueChanged.AddListener(delegate{AudioDisabledToggle();});
        Debug.Log(GameSettings.index);
        applyButton.onClick.AddListener(delegate{OnApplyButtonClick();});
        LoadSettings();
    }
    public void AudioDisabledToggle()
    {
        Debug.Log(gameSettings.audioEnabled);
        gameSettings.audioEnabled = AudioListener.pause = !audioEnabled.isOn;
    }
    public void OnApplyButtonClick()
    {
        SaveSettings();
        foreach (GameObject gameObject in GameObject.FindGameObjectsWithTag("Settings"))
        {
            GetComponent<AudioSource>().Play();
            gameObject.SetActive(false);
        }
    }
    public void SaveSettings()
    {
        string jsonData = JsonUtility.ToJson(gameSettings, true);
        File.WriteAllText(Application.persistentDataPath + "/gameSettings.json", jsonData);
        Debug.Log("Saved");
    }
    public void LoadSettings()
    {
        File.ReadAllText(Application.persistentDataPath + "/gameSettings.json");
        gameSettings = JsonUtility.FromJson<GameSettings>(File.ReadAllText(Application.persistentDataPath + "/gameSettings.json"));
        Debug.Log("Loaded");
        audioEnabled.isOn = !gameSettings.audioEnabled;
        //Debug.Log("Loaded");
    }
}

这些脚本以前工作但最近我收到此错误

  

NullReferenceException：未将对象引用设置为对象的实例

这些行audioEnabled.isOn = !gameSettings.audioEnabled;和AudioListener.pause = gameSettings.audioEnabled = !audioEnabled.isOn;存在问题，我发现此类中的audioEnabled存在问题

public class GameSettings{

    // Use this for initialization
    public bool audioEnabled;
    public static bool index;
}

我不知道问题是什么，因为当我将这个场景与我在其他项目中导出的脚本一起使用时，除了我正在处理的当前项目马上。请帮忙。