Unity keeps crashing in while loop

Hello, the next code creates a random position and then checks if the position isn't behind a wall or another object. If the position is behind another object, then it creates a new position untill it isn't behind a wall.

The code works how I want it to be, but unity keeps crashing after 30-60 seconds, even with a filter that always leaves the loop after 15 fails.

This is the code: using UnityEngine; using System.Collections;

 /// <summary>
 /// 1. Maak een empty game object en noem het SpawnManager.
 /// 2. Voeg het player object toe aan dit script.
 /// 3. Voeg iedere soort enemy toe die aan het begin van de game zichtbaar moet zijn.
 /// </summary>
 
 public class FishSpawner : MonoBehaviour{
 
     public float timer = 10;            // Time between every spawn
     public float maxRange = 75;            // Max range between player and spawnpoint
     public GameObject player;            // Player object to define the spawn positions
     public GameObject[] prefabs;        // Array with prefabs to spawn.
 
     private int layer = 1;                // Check in wich layer the player is.
     private IEnumerator coroutine;
 
     void Start()
     {
         // Start coroutine function
         coroutine = Spawn(timer);
         StartCoroutine(coroutine);
     }
 
 
     private IEnumerator Spawn(float waitTime) {
         while (true) {
             yield return new WaitForSeconds(waitTime);
 
             // Get player position
             float posX = player.transform.position.x;
             float posY = player.transform.position.y;
             float posZ = player.transform.position.z;
 
             // Check the layer where the player is
             if(posY > 399){
                 layer = 1;
                 maxRange = 30;
             }else if(posY > 299){
                 layer = 2;
                 maxRange = 60;
             }else if(posY > 199){
                 layer = 3;
                 maxRange = 100;
             }else if(posY > 99){
                 layer = 4;
                 maxRange = 125;
             }
 
             // Select a random object in the prefab array.
             int spawnPointIndex = Random.Range (0, layer -1);
 
             Vector3 spawnPosition = new Vector3(0,0,0);
 
             // New random spawn position
             spawnPosition = getPosition(posX, posY, posZ);
 
             // check for the while loop
             bool repeat = true;
             int exitCounter = 0;
 
             // Setting up the arraycast to check if there is an object between the player and the spawnpoint
             RaycastHit hit;
             Ray landingray = new Ray (player.transform.position, spawnPosition);
 
 
             while (repeat) {
                 // If exit counter equals 15, leave the while loop.
                 if (exitCounter == 15) {
                     repeat = false;
                 }
                 // unvalid position to spawn
                 if (Physics.Raycast (landingray, out hit, maxRange)) {
                     Debug.Log ("Recalculating spawn location.");
                     spawnPosition = getPosition(posX, posY, posZ);
                     landingray = new Ray (player.transform.position, spawnPosition);
                     exitCounter++;
                     repeat = true;
                 } 
                 // position is valid and object is spawned
                 else {
                     // object is klaar om gespawned te worden.
                     Debug.Log ("Object is ready to spawn.");
                     Instantiate (prefabs [spawnPointIndex], spawnPosition, new Quaternion (0, 0, 0, 0));
                     repeat = false;
                 }
             }
 
         }
     }
 
     Vector3 getPosition(float posX, float posY, float posZ){
         // create random position
         float randomX = Random.Range (posX - maxRange, posX + maxRange);
         float randomY = Random.Range (posY - maxRange, posY + maxRange);
         float randomZ = Random.Range (posZ - maxRange, posZ + maxRange);
         if (randomY > 360) {
             randomY = 360;
         }
 
         // Position van het nieuwe spawnpunt
         return new Vector3 (randomX, randomY, randomZ);
     }
 }