Array Index is out of Range and I don't understand why.

I'm not entirely sure what Code to include in this. Basically Im working with a deck of cards. I created a scene to create the deck and shuffle it and generally act as a deck, and it all works fine. But when I created a new scene and used the deck as a prefab I started getting an IndexOutOfRangeException.

 public void ToggleFace(bool showFace){
         if (showFace) {
                 spriteRenderer.sprite = faces[cardIndex];
             }
                                                 
         } else {
             spriteRenderer.sprite = cardBack;
         }
     }
 

After doing some debugging I found out the exception happens always on the first 'card' that is being created. To be honest It looks as though other than the exception being thrown it all runs. But Im guessing that somehow an instance from the faces array is being called before its created, but I dont understand why since the faces array is filled in the inspector. What should I do?

EDIT: In another script I have:

 void ShowCards(){
         int cardCount = 0;
         if (deck.HasCards) {
             int k = 0;
             foreach (Card i in deck.GetCards()) { 
                 float co = cardOffset * cardCount;
                 Vector3 temp = start + new Vector3 (co, 0f);
                 i.transform.position = temp;
 
                 if (i.getColorSuit () == ColorSuit.Blue) {
                     if (i.getBidAction () == BidAction.None) {
                         if (i.getCardValue () == 3) {
                             k = 20;
                         }
                         if (i.getCardValue () == 4) {
                             k = 22;
                         }
                         if (i.getCardValue () == 5) {
                             k = 7;
                         }
                     }
                     if (i.getBidAction () == BidAction.Getaway) {
                         k = 19;
                     }
                 }
                 i.cardIndex = k;
                 i.ToggleFace (true);                      
                 SpriteRenderer spriteRenderer = i.GetComponent<SpriteRenderer> ();
                 spriteRenderer.sortingOrder = deck.CardCount () - cardCount;
 
                 cardCount++;
 
             }
         }
     }

 

I cut a lot of the stuff for showing what causes k to be whatever number it is but you get the idea I think (k can be from 0-23 since that is how many card faces I have). And the error is pointing to where it gets called :

 void Update(){
         if (cardCounter != deck.CardCount ()) {
             cardCounter = deck.CardCount();
             ShowCards();
         }
     }