Hardcrash when using GetPixels

I have some pretty simple code- I get the pixels of a texture and then check to see how many of those pixels are clear. Here's the issue: It hard freezes Unity whenever I run it.

Two Q's: 1- Any idea why? The portion that freezes is the "checkTexture()" function 2- Is there a smarter way to be checking how many pixels are x color?

UPDATE- Its definitely the loop that's crashing this. But why?

 using UnityEngine;
 using System.Collections;
 
 public class scratchoffManager : MonoBehaviour {
     public GameObject front;
     public GameObject back;
     private Texture2D texture;
     
     private Color[] pixelHitBlock = new Color[400];
     private gameManager manager;
     
     private int curTexSize;
     private Color[] currentTex;
     private int clearCounter;
     void Start () {
         manager = GameObject.Find ("gameManager").GetComponent<gameManager>();
         
         for(int i = 0; i < pixelHitBlock.Length; i++){
             pixelHitBlock[i] = new Color(0f,0f,0f,0f);
         }
     }
     
     public void setTexture(Texture2D newTex){
         back.renderer.material.mainTexture = newTex; //setTexture
         Debug.Log("Set back tex?");
         texture = Instantiate(front.renderer.material.mainTexture) as Texture2D;  //clone the material
         front.renderer.material.mainTexture = texture; //set the material equal to the clone   
         
         curTexSize = texture.height * texture.width;
         currentTex = new Color[curTexSize];
         
         StartCoroutine("checkTimer");
     }
     
     public void adjustTexture(Vector2 texCo){ //always come in a s0,0
         int x = Mathf.FloorToInt(texCo.x * texture.width);
         int y = Mathf.FloorToInt(texCo.y * texture.height);
         Debug.Log("pixel hit at" + x + "," + y);
                 
         texture.SetPixels(x,y,20,20,pixelHitBlock);
         texture.Apply();
     }
     
     private void checkTexture(){
         Debug.Log("Checking the texture");
         currentTex = texture.GetPixels(0,0,texture.width,texture.height);
         Debug.Log("Checking the texture 2");
         for(int i = 0; i < currentTex.Length; i++){
             if(currentTex[i] == Color.clear){
                 clearCounter++;
                 Debug.Log("Checking the texture" + i);
             }
             Debug.Log("Clear counter:" + clearCounter);
             clearCounter = 0;
         }
     }
     
     IEnumerator checkTimer(){
         yield return new WaitForSeconds(1.5f);
         
         checkTexture();
         StartCoroutine("checkTimer");
     }
 }