#Need Fast Help# NullReferenceException: Object reference not set to an instance of an object

using UnityEngine; using System.Collections;

public class DetectTouchesAndClicks : MonoBehaviour {

 // Use this for initialization
 void Start () {
 
 }
 
 // Update is called once per frame
 void Update () {
     if (Input.GetMouseButton(0))
     {
         Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
         RaycastHit hit;
         if(Physics.Raycast(ray,out hit))
         { 
             Debug.Log("ObjectName:" + hit.collider.name, hit.collider.gameObject);
             hit.collider.SendMessage ("Touched", SendMessageOptions.DontRequireReceiver);
         }
     }
     if (Input.touchCount > 0)
     {
         foreach (Touch touch in Input.touches)
         {
             Ray ray = Camera.main.ScreenPointToRay((Vector3)touch.position);
         RaycastHit hit;
         if(Physics.Raycast(ray,out hit))
         {
                 Debug.Log("ObjectName:" + hit.collider.name, hit.collider.gameObject);
                 hit.collider.SendMessage ("Touched", SendMessageOptions.DontRequireReceiver);
         }
     }

     }


 
 }

}