Why does this make unity crash?

using UnityEngine; using System; using System.Collections;

public class RTScontroller : MonoBehaviour {

 int lastScroll = 0;    // last screen's scroll, used for velocity
 float ZOOM_ANGLE = 6;    // denominator of the radian degree used for zooming
 float wheelVelocity = 0;  // used for zoom velocity
 float thisScroll;    // float thisScroll = Input.GetAxis("Mouse ScrollWheel");
 float horzKeys;    // horizontal key movent relative to scrollSpeed
 float vertKeys;    // vertical movement relative to scroll
 float yScroll; // = Input.GetAxis("Mouse ScrollWheel"); //store input, used primarily for +/-
 float forwardScroll; // = Input.GetAxis("Mouse ScrollWheel");// same ^^
 
 public const int MIN_Y = 40;
 public const int MAX_Y = 400; 
 public const int scrollSpeed = 15;    // Camera's movement speed
 public const float VELOCITY_SCALE = 1;  // used to scale zoom velocity
 
 // Use this for initialization
 void Start()
 {



 }

 // Update is called once per frame
 void Update()
 {
     
     // mouse move method

     // do movement by mousePosition

     // screen Right
     if (Input.mousePosition.x > Screen.width) { transform.Translate(Vector3.right * scrollSpeed); }
     //screen left
     if (Input.mousePosition.x < 0) { transform.Translate(Vector3.left * scrollSpeed); }
     // screen up
     if (Input.mousePosition.y > Screen.height) { transform.Translate(Vector3.forward * scrollSpeed); }
     //screen down
     if (Input.mousePosition.y < 0) { transform.Translate(Vector3.forward * -scrollSpeed); }

     //keybord move method
     // Do camera movement by keyboard
     horzKeys = (Input.GetAxis("Horizontal") * scrollSpeed);
     vertKeys = (Input.GetAxis("Vertical") * scrollSpeed);
     transform.Translate(horzKeys, 0, vertKeys);
     
     // Do zoom by mouse wheel
     //thisScroll = Input.GetAxis("Mouse ScrollWheel");
    velocityUpdate();  // Updates wheel velocity in order to continue acceleration of zoom feature
    

     float rotationSpeed = ((float)Math.PI * (float)wheelVelocity) / ZOOM_ANGLE;  // use wheelVelocity to get correct angle scale and direction
     /* because the change in camera height is dependant on wheelVelocity, so must be the angle at which we rotate during the zoom.
     if we multiply the angle by the velocity, the angle should rotate the same relative to the speed of the scroll*/
     
     
     
     
     while ( transform.position.y > MIN_Y && transform.position.y < MAX_Y )
     {
     
          //yScroll = Input.GetAxis("Mouse ScrollWheel") * wheelVelocity;
         forwardScroll = Input.GetAxis("Mouse ScrollWheel") * wheelVelocity;
         transform.Translate(0, Input.GetAxis("Mouse ScrollWheel") * wheelVelocity, Input.GetAxis("Mouse ScrollWheel") * wheelVelocity);

         if (thisScroll > 0) { transform.Rotate((Vector3.up * rotationSpeed)); }
         if (thisScroll < 0) { transform.Rotate((Vector3.up * rotationSpeed)); }

     
     }

 }

 
     
 
 /*

RTScontroller.velocityUpdate() : currently private use : accelerated zoom feature for game camera takes an input reading from a mouse wheel ( -1 < x < 1 ) and increments the wheelVelocity complete stop is recognized as 2 frames of no movement use VELOCITY_SCALE to increase the ammount of acceleration */ void velocityUpdate() {

     if ((lastScroll == 0) && (thisScroll == 0)) { wheelVelocity = 0; }// if no scroll, reset velocity to zero

     else
     {        //prioritize input decisions by clearly seperating no scroll option

         if (thisScroll != 0)
         {             // if thisScroll isnt zero, the following will compound velocity

             if (lastScroll > 0 && thisScroll > 0) { wheelVelocity++; }; // if positive scroll, increase velocity

             if (lastScroll > 0 && thisScroll < 0) { wheelVelocity = -1; }; // quickly switches to opposite scroll

             if (lastScroll < 0 && thisScroll < 0) { wheelVelocity--; }; // if negative scroll, decrement velocity

             if (lastScroll < 0 && thisScroll > 0) { }
         }
         else { wheelVelocity = lastScroll; }         // if this scroll is zero, prepare to stop. used for soft deceleration
     }

     // end the funtion by adding a constant to scale velocity effect

     wheelVelocity = wheelVelocity * VELOCITY_SCALE;
 }
 
 
 
 

//end class
}