NullReferenceException: Object reference not set to an instance of an object at Player.Update () [0x00000] in :0 (Filename: Line: -1)

my project is run well in editor but when i build it for pc or for android it run very weird not even a game, when i check output_log

i get this in output_log

NullReferenceException: Object reference not set to an instance of an object at Player.Update () [0x00000] in :0

(Filename: Line: -1)

idk where is the error in this code :

using System.Collections; using System.Collections.Generic; using UnityEngine; using UnityEngine.SceneManagement; using UnityEngine.UI;

public class Player : MonoBehaviour {

 public float Yincrement;
 public float speed;
 public float maxHeight;
 public float minHeight;

 public int health = 3;
 public GameObject effect;
 public Text healthDisplay;
 public GameObject gameOver;
 

 private Vector2 targetPos;

 public int Health
 {
     get
     {
         return health;
     }

     set
     {
         health = value;
     }
 }

 void Update ()
 {
     healthDisplay.text = health.ToString();

     if (health <= 0)
     {
         
         gameOver.SetActive(true);
     }


     transform.position = Vector2.MoveTowards(transform.position, targetPos, speed * Time.deltaTime);

     if (Input.GetKeyDown(KeyCode.UpArrow) && transform.position.y < maxHeight) {
        
         Instantiate(effect, transform.position, Quaternion.Euler(90,0,0));
         targetPos = new Vector2(transform.position.x, transform.position.y + Yincrement);
     } else if (Input.GetKeyDown(KeyCode.DownArrow)&& transform.position.y > minHeight)
     {
         
         Instantiate(effect, transform.position, Quaternion.Euler(90, 0, 0));
         targetPos = new Vector2(transform.position.x, transform.position.y - Yincrement);
     }

 }

}

can somone tell me where is the error in this code, i see other question like this the uotput_log show the number of the line that error in there but mine is weird