After instantianting gameobjects, unity cant asign references anymore

Basically, I am making a game where you run over chicken with a car, I have everything done, EXCEPT, the spawning script. To spawn chickens I use this script: using UnityEngine; using System.Collections;

 public class Spawener_Chicken : MonoBehaviour
 {
     public GameObject Chicken;
     public int xPos;
     public int zPos;
     public int enemyCount;
     public int enemyLimit = 100;
 
     
     void Start()
     {
         StartCoroutine(EnemySpawn());
     }
     void Update()
     {
        
     }
     IEnumerator EnemySpawn()
     {
         while (enemyCount < enemyLimit)
         {
             xPos = Random.Range(-30, 30);
             zPos = Random.Range(-22, 22);
             Instantiate(Chicken, new Vector3(xPos, 1, zPos), Quaternion.identity);
             yield return new WaitForSeconds(0.1f);
             enemyCount += 1;   
         } 
         while (enemyCount >= enemyLimit)
         {
             StartCoroutine(EnemySpawn());
         }
     }
 
 }

After spawning some, Unity starts giving out errors and pausing the game. This Is the error:

 NullReferenceException: Object reference not set to an instance of an object
 chicken.OnTriggerEnter (UnityEngine.Collider hit) (at Assets/scripts/chicken.cs:60)

And This is the Chicken code:

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using UnityEngine.AI;
 
 public class chicken : MonoBehaviour
 {
    private NavMeshAgent NMA;
     public int testint1 = 99;
     public int testint2;
    private GameObject Visuals;
    private GameObject ParticleSys;
     public GameObject NumberBoy;
     public Spawener_Chicken SpawnerCode;
     void Start()
     {
         StartCoroutine(wait());
     }
 
     void RealStart()
     {
         NumberBoy = GameObject.Find("/Car/Spawner for enemys");
         SpawnerCode = NumberBoy.GetComponent<Spawener_Chicken>();
         InvokeRepeating("ChangeDestination", 0, 5);
         NMA = GetComponent<NavMeshAgent>();
         Visuals = this.gameObject.transform.GetChild(0).gameObject;
         ParticleSys = this.gameObject.transform.GetChild(1).gameObject;
     }
 
     IEnumerator wait()
     {
         yield return new WaitForSeconds(1);
 
         RealStart();
     }
 
     public Vector3 RandomNavmeshLocation(float radius)
     {
         Vector3 randomDirection = Random.insideUnitSphere * radius;
         randomDirection += transform.position;
         NavMeshHit hit;
         Vector3 finalPosition = Vector3.zero;
         if (NavMesh.SamplePosition(randomDirection, out hit, radius, 99999999))
         {
             finalPosition = hit.position;
         }
         return finalPosition;
     }
     void ChangeDestination()
     {
        // Debug.Log("Changed destination");
         NMA.SetDestination(RandomNavmeshLocation(testint1));
     }
 
     private void OnTriggerEnter(Collider hit)
     {
         if (hit.gameObject.tag == "Car")
         {
             testint1 = 0;
             Visuals.SetActive(false);
             ParticleSys.SetActive(true);
            SpawnerCode.enemyCount--;
             //  Debug.Log(gameObject.name + ": THat GUY JUST HIT ME!");
             Destroy(gameObject, 2);
         }
 
         if (hit.gameObject.tag == "Destroying Wall")
         {
             SpawnerCode.enemyCount--;
             Destroy(gameObject, 0);
         }
 
     }
   
 }