How do I stop my timer script from crashing unity?

So, I tried to make an easily accessible and reusable timer script. But every time I use the CountDown function I made the game crashes. However, the scripts themselves don't give me any errors so I'm very confused as to what's going on. Here's the code:

Timer Script:

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

 public class Timer : MonoBehaviour
 {
     public Text TimerText;
     private float TimerNumber = 1; 
     private float StartTime;
     private float time;
     private bool Finished = false;
     public bool TimerDone = false; 
     private bool countingDown; 
 
     void Awake()
     {
         TimerText.enabled = false;
     }
 
     void Start()
     {
         StartTime = Time.time;
     }
 
     void Update()
     {
         float time = Time.time - StartTime;
     }
 
     public void CountDown(float countDownFrom)
     {
         TimerDone = false; 
         TimerText.enabled = true; 
         countingDown = true; 
         while(countingDown == true)
         {
             TimerNumber = countDownFrom - time;
             string Seconds = ((int)TimerNumber).ToString();
             TimerText.text = Seconds;
 
             if (TimerNumber == 0)
             {
                 countingDown = false; 
                 Finished = true;
                 TimerText.enabled = false;
                 TimerNumber = 1;
             }
         }
          
         if (Finished == true)
         {
             Finished = false;
             TimerDone = true; 
         }
     }
 }

The script that I'm trying to access it from:

 using UnityEngine;
 
 public class TurnChanger : MonoBehaviour
 {
     public GameObject TimerBlock;
     private Timer timer; 
 
     void Awake()
     {
         timer = TimerBlock.GetComponent<Timer>(); 
     }
 
     void Update()
     {
  #region TestConponents
 
         if (Input.GetKeyDown("1"))
         {
             timer.CountDown(10); 
         }
 
         if (timer.TimerDone == true)
         {
             print("The Timer is finished"); 
         }
 #endregion
     }

I only included the part of the script that has to do with the Timer but here's the whole thing just in case:

 using UnityEngine;
 
 public class TurnChanger : MonoBehaviour
 {
 
     public bool GameStart = false;
     public bool GamePlaying = false;
     public GameObject GameManger; 
     public CardCreation cardCreateionScript;
     public GameObject DeckSlot;
     public GameObject TeleportingCard;
     public Vector3 Displacement;
     public int randomCardNumber; 
     private int indexNumber = 0;
     private int indexNumber2 = 0; 
     public float yDisplacementRate;
     public int numberOfStartingCards;
     private int numberOfDrawnCards = 0;
     public GameObject TimerBlock;
     private Timer timer; 
     void Awake()
     {
         timer = TimerBlock.GetComponent<Timer>(); 
         cardCreateionScript = GameManger.GetComponent<CardCreation>();
     }
 
     void Update()
     {
         randomCardNumber = Random.Range(0, cardCreateionScript.YourDeck.Count - 1);
 
         #region TestConponents
 
         if (Input.GetKeyDown("1"))
         {
             timer.CountDown(10); 
         }
 
         if (timer.TimerDone == true)
         {
             print("The Timer is finished"); 
         }
 
         if (Input.GetKeyDown("space"))
         {
             GameStart = true;
             print("Game Started!"); 
         }
 
         #endregion
 
         if (GameStart == true)
         {
             GameStart = false;
             GamePlaying = true;
             StartGame();
         }
     }
         public void StartGame()
          {
             print("Game Playing!"); 
             BuildDeck();
 
             if(BuildDeck() == true)
              {
             DrawHand();
 
             if(DrawHand() == true)
                 {
                 StartTurn();
                 }
              }
 
          }
     
     public bool BuildDeck()
     {
         print("Building The Deck");
 
         while (indexNumber != cardCreateionScript.YourDeck.Count) {
             TeleportingCard = cardCreateionScript.YourDeck[indexNumber]; 
             TeleportingCard.GetComponent<Transform>().position = DeckSlot.GetComponent<Transform>().position + Displacement;
             Displacement.y += yDisplacementRate; 
             indexNumber = indexNumber + 1; 
                                                                   }
         indexNumber = 0; 
         return true; 
     }
 
     public bool DrawHand()
     {
         print("Drawing Your Hand");
 
         while(numberOfDrawnCards != numberOfStartingCards)
         {
             if(cardCreateionScript.YourHand[indexNumber2].GetComponent<HandSlot>().open == true)
             {
                 cardCreateionScript.YourHand[indexNumber2].GetComponent<HandSlot>().card = cardCreateionScript.YourDeck[randomCardNumber]; 
                 cardCreateionScript.YourDeck.RemoveAt(randomCardNumber); 
                 numberOfDrawnCards = numberOfDrawnCards + 1;
                 print("Drew " + numberOfDrawnCards + " Cards");
                 indexNumber2 = indexNumber2 + 1;
                 print("Added To IndexNumber2");
 
                 if (indexNumber2 == numberOfStartingCards - 1)
                 {
                     break; 
                 }
             }
 
         }
 
         return true;
     }
 
     public bool StartTurn()
     {
         print("Starting Your Turn"); 
         return true; 
     }
 }