Dúvida sobre código com NullReferenceException

Estou tentando fazer um jogo da memoria no Unity e nessa parte do código surgiu esse erro e não consigo resolver:

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

public class PictureManager : MonoBehaviour
{
    public Picture PicturePrefab;
    public Transform PicSpawnPosition;
    public Vector2 StartPosition = new Vector2(-2.15f, 3.62f);

    [Space] [Header("End Game Screen")]
    public GameObject EndGamePanel;

    public GameObject NewBestScoreText;
    public GameObject YourScoreText;
    public GameObject EndTimeText;

   [...]

    private bool _corutineStarted = false;

    private int _pairNumbers;
    private int _removedPairs;
    private Timer _gameTimer;

    void Start()
    {
        CurrentGameState = GameState.NoAction;
        CurrentPuzzleState = PuzzleState.CanRotate;
        PuzzleRevealedNumber = RevealedState.NoRevealed;
        _revealedPicNumber = 0;
        _firstRevealedPic = -1;
        _secondRevealedPic = -1;

        _removedPairs = 0;
        _pairNumbers = (int) GameSettings.Instance.GetPairNumber();

        _gameTimer = GameObject.Find("Main Camera").GetComponent<Timer>();
        
        [...]
private void DestroyPicture()
{
    PuzzleRevealedNumber = RevealedState.NoRevealed;
    PictureList[_picToDestroy1].Deactivate();
    PictureList[_picToDestroy2].Deactivate();
    _revealedPicNumber = 0;
    _removedPairs++;
    CurrentGameState = GameState.NoAction;
    CurrentPuzzleState = PuzzleState.CanRotate;
}

private IEnumerator FlipBack()
{
    _corutineStarted = true;

    yield return new WaitForSeconds(0.5f);

    PictureList[_firstRevealedPic].FlipBack();
    PictureList[_secondRevealedPic].FlipBack();

    PictureList[_firstRevealedPic].Revealed = false;
    PictureList[_secondRevealedPic].Revealed = false;

    PuzzleRevealedNumber = RevealedState.NoRevealed;
    CurrentGameState = GameState.NoAction;

    _corutineStarted = false;
}

private void LoadMaterials()
{
    var materialFilePath = GameSettings.Instance.GetMaterialDirectoryName();
    var textureFilePath = GameSettings.Instance.GetPuzzleCategoryTextureDirectoryName();
    var pairNumber = (int)GameSettings.Instance.GetPairNumber();
    const string matBaseName = "Pic";
    var firstMaterialName = "Back";

    for(var index = 1; index <= pairNumber; index++)
    {
        var currentFilePath = materialFilePath + matBaseName + index;
        Material mat = Resources.Load(currentFilePath, typeof(Material)) as Material;
        _materialList.Add(mat);

        var currentTextureFilePath = textureFilePath + matBaseName + index;
        _texturePathList.Add(currentTextureFilePath);
    }
    _firstTexturePath = textureFilePath + firstMaterialName;
    _firstMaterial = Resources.Load(materialFilePath + firstMaterialName, typeof(Material)) as Material;
}

void Update()
{
  if (CurrentGameState == GameState.DeletingPuzzles)
    {
        if(CurrentPuzzleState == PuzzleState.CanRotate)
        {
            DestroyPicture();
            CheckGameEnd();
        }
    }

  if (CurrentGameState == GameState.FlipBack)
    {
        if (CurrentPuzzleState == PuzzleState.CanRotate && _corutineStarted == false)
        {
            StartCoroutine(FlipBack());
        }
    }
    
  if (CurrentGameState == GameState.GameEnd)
    {
        if (PictureList[_firstRevealedPic].gameObject.activeSelf == false &&
            PictureList[_secondRevealedPic].gameObject.activeSelf == false &&
            EndGamePanel.activeSelf == false)
        {
            ShowEndGameInformation();
        }
    }
}

private bool CheckGameEnd()
{
    if (_removedPairs == _pairNumbers && CurrentGameState != GameState.GameEnd)
    {
        CurrentGameState = GameState.GameEnd;
        _gameTimer.StopTimer();
    }

    return (CurrentGameState == GameState.GameEnd);
}

private void ShowEndGameInformation()
{
    EndGamePanel.SetActive(true);
    YourScoreText.SetActive(true);

    var timer = _gameTimer.GetCurrentTime();
    var minutes = Mathf.Floor(timer / 60);
    var seconds = Mathf.RoundToInt(timer % 60);
    var newText = minutes.ToString("00") + ":" + seconds.ToString("00");
    EndTimeText.GetComponent<Text>().text = newText;
}

NullReferenceException: Object reference not set to an instance of an object PictureManager.ShowEndGameInformation () (at Assets/Scripts/PictureManager.cs:257) A linha 257 é essa EndTimeText.GetComponent().text = newText; e é como se não tivesse definida. Por favor, alguém sabe como resolver?