object reference not set to instance of an object On last line

public class PlayerScoreScript : MonoBehaviour {

 [SerializeField]
 public AudioClip  coinClip, lifeClip, finishclip;
 private CameraScript CameraScript;
 private Vector3 previousPosition;
 private bool countScore;


 public GameObject deathParticle;

 private PlayerMovement player;


 public static int scoreCount;
 public static int lifeCount;


 public static int coinCount;

 void Awake(){
     CameraScript = Camera.main.GetComponent<CameraScript> ();
 }


 // Use this for initialization
 void Start () {

     player = FindObjectOfType<PlayerMovement> ();
     previousPosition = transform.position;
     countScore = true;

 }

 void Update () {
     CountScore();
 }

 void CountScore (){
     if(countScore){
         if(transform.position.y < previousPosition.y){
             scoreCount++;
         }
         previousPosition = transform.position;
         GamePlayController.instance.SetScore (scoreCount);
     }
 
 }



         void OnTriggerEnter2D(Collider2D target){
             if(target.tag =="Coin"){
                 coinCount++;
                 scoreCount+=200;
                 AudioSource.PlayClipAtPoint(coinClip,transform.position);
                 target.gameObject.SetActive(false);

         GamePlayController.instance.SetScore (scoreCount);
         GamePlayController.instance.SetCoinScore (coinCount);
         }
             if(target.tag =="Life"){
                 lifeCount++;
                 scoreCount+=300;
                 AudioSource.PlayClipAtPoint(lifeClip,transform.position);
                 target.gameObject.SetActive(false);
         GamePlayController.instance.SetScore (scoreCount);
         GamePlayController.instance.SetLifeScore (lifeCount);
             }

     if (target.tag == "Key") {
         coinCount++;
         scoreCount += 500;
         AudioSource.PlayClipAtPoint (finishclip, transform.position);

     
        
     }


         target.gameObject.SetActive(false);

     if(target.tag=="Bounds" || target.tag == "Deadly"){

         Instantiate (deathParticle,player.transform.position, player.transform.rotation);


                 CameraScript.moveCamera=false;
         countScore=false;
         transform.position=new Vector3(500,500,0);
                 lifeCount--;

 
         GameManager.instance.CheckGameStatus (scoreCount, coinCount, lifeCount);