Unity freezes on play mode

Hey everyone! I've been trying to build a flocking simulation with fishes and one of my friends helped me to fix part of it and it worked very well on her computer, however, when I tried it on mine it kept freezing everytime I pressed play.

Some people told me it could be an infinite loop, but I'm not sure if that's the problem.

Here is my scripts:

Boid.cs

//using System; using System.Collections; using System.Collections.Generic; using System.Dynamic; using UnityEngine;

public class Boid : MonoBehaviour {

 private static Boid _instance = null;
 private static object _lock = new object();

 public static Boid Instance { 
     get
     {
         lock (_lock)
         {
             if (_instance != null) return _instance;
             Boid boid = FindObjectOfType<Boid>();
             if (boid == null)
             {
                 GameObject go = new GameObject("[Boid]", typeof(Boid));
                 boid = go.GetComponent<Boid>();
             }
             _instance = boid;
         }
         return _instance;
     }
 }

 public GameObject fishPrefab;
 public GameObject goalPrefab;
 public float goalRange = 1f;
 public int tankSize = 10;

 //generate number of fishes
 static int numFish = 10;
  
 private GameObject[] _allFish = new GameObject[numFish];
 public GameObject[] allFish
 {
     get { return _allFish; }
 }

 //public static Vector3 goalPos = Vector3.zero;
 public Vector3 goalPos 
 {
     get 
     {
         if(goalPrefab != null) return goalPrefab.transform.position;
         return Vector3.zero;
     } 
 }

 // Start is called before the first frame update
 void Start()
 {
     //create loop interating through the numFish array
     for (int i = 0; i < numFish; i++)
     {
         //create a postion to our fishes (in a 3Dimensional space)
         allFish[i] = (GameObject)Instantiate(fishPrefab, 
             Random.insideUnitSphere * tankSize, 
             Quaternion.identity);
     }
 }

 // Update is called once per frame
 void Update()
 {
     //Reset where the goal position is randomly 
     foreach(var fish in allFish)
     {
         if((fish.transform.position - goalPos).magnitude <= goalRange)
         {
             goalPrefab.transform.position = Random.insideUnitSphere * tankSize * 0.75f;
             break;
         }
     }
 }

}

Flock.cs

using System.Collections; using System.Collections.Generic; using UnityEngine;

public class Flock : MonoBehaviour { public float speed = 1f; float rotationSpeed = 4.0f; Vector3 averageHeading; Vector3 averagePosition; //value of the neighbor distance float neighbourDistance = 3.0f; float minDistance = 1f;

 bool turning = false;

 // Start is called before the first frame update
 void Start()
 {
     //generate a small difference in each neighbor's speed
     speed = Random.Range(0.5f, 1);
 }

 // Update is called once per frame
 void Update()
 {
     if (Vector3.Distance(transform.position, Vector3.zero) >= Boid.Instance.tankSize)
         turning = true;
     else
         turning = false;

     if (turning)
     {
         Vector3 direction = Vector3.zero - transform.position;
         transform.rotation = Quaternion.Slerp(transform.rotation, Quaternion.LookRotation(direction), rotationSpeed * Time.deltaTime);
         speed = Random.Range(0.9f, 1f);
     }
     else
     {
         //flock value
         if (Time.frameCount % 5 == 0)
             ApplyRules(); //function called every 5 times
     }
     transform.Translate(0, 0, Time.deltaTime * speed);
 }

 void ApplyRules()
 {
     GameObject[] allFish = Boid.Instance.allFish;

     // Cohesion of boids
     Vector3 vcentre = Vector3.zero; //center of group
     Vector3 vavoid = Vector3.zero; //points away from any neighbors
     //group speed
     float gSpeed = 0.1f;

     //goal position
     Vector3 goalPos = Boid.Instance.goalPos;

     float dist; //distance variable

     //calculate group size
     int groupSize = 0;
     foreach (GameObject fish in allFish)
     {
         if (fish != this.gameObject)
         {
             dist = Vector3.Distance(fish.transform.position, this.transform.position);
             if (dist <= neighbourDistance)
             {
                 vcentre += fish.transform.position;
                 groupSize++;

                 if (dist < minDistance)
                 {
                     vavoid = vavoid + (this.transform.position - fish.transform.position);
                 }
                 //average speed of group by adding the speed of the flock
                 Flock anotherFlock = fish.GetComponent<Flock>();
                 gSpeed = gSpeed + anotherFlock.speed;
             }
         }
     }

     if (groupSize > 0)
     {
         //calculate average centre and average speed
         vcentre = vcentre / (float)groupSize + (goalPos - this.transform.position);
         speed = gSpeed / (float)groupSize;

         Vector3 direction = (vcentre + vavoid) - transform.position;
         if (direction != Vector3.zero)
         {
             transform.rotation = Quaternion.Slerp(transform.rotation, Quaternion.LookRotation(direction), rotationSpeed * Time.deltaTime);
         }
     }
 }

}