Deleted object tagged as missing instead of null.

Hello, I have a smaller question.

I have a cript that creates a grid made out of cubes.After the grid is created the game than randomly chooses some objects from a list and deletes them.

My problem is when I delete this object, the reference in the editor marks the object as missing. I understand that the object has reference to the neighbour but when it gets deleted the object canˇt find the its neighbour. My question is how could I avoid this or repair it ?

Here is my script.

Map generator public class MapGenerator : MonoBehaviour { public int mapSize; public int numberOfWaterHoles;

     public CubeCell cubeCell;
     public List<CubeCell> cubeCells = new List<CubeCell>();
 
     public bool landIsGenerated;
     public int i;
     public bool generateLand;
     void Start()
     {
         
         GenerateMap();
     }
 
     void GenerateMap() 
     {
         for (int x = 0 ; x < mapSize; x++)
         {
             for (int z = 0; z < mapSize; z++)
             {
                 CreateTile(x, z, i++);
             }
         }
 
         if (i == mapSize * mapSize) { landIsGenerated = true; } else { landIsGenerated = false; }
 
         if (landIsGenerated) 
         { 
             CreateWater();
         }
     }
 
     void CreateTile(int x,int z,int i) 
     {
         Vector3 tilePosition;
         tilePosition.x = x * 1f;
         tilePosition.y = 0;
         tilePosition.z = z * 1f;
 
         CubeCell cubeTile = Instantiate<CubeCell>(cubeCell);
   
         cubeCells.Add(cubeTile);
         cubeTile.transform.SetParent(transform, false);
         cubeTile.transform.localPosition = tilePosition;
 
         if (z > 0) { CubeCell.GetNeighbours_EastAndWest(cubeTile, cubeCells[i - 1]); }
         if (x > 0) { CubeCell.GetNeighbours_NorthAndSouth(cubeTile, cubeCells[i - mapSize]); }
         
     }
   void CreateWater() 
     {
         //Choose random number from a list delete the gameobject,empty space will be used to simulate water.Remaining objects will be used as land.
         
         for (int o = 0; o < numberOfWaterHoles; o++)
         {
 
             int randomNumber = Random.Range(o, (mapSize*mapSize));
 
             var randomObject = new CubeCell[numberOfWaterHoles];
             randomObject[o] = cubeCells[randomNumber];
 
             cubeCells[randomNumber] = cubeCells[o];
             cubeCells[o] = randomObject[o];
             cubeCells[o].DestroyObject(); 
         }        
     }    
 }

Cell script

 public class CubeCell : MonoBehaviour
 {
     [Header("Neighbours")]
     public CubeCell east, north, west, south;
 
     [Header("Land types")]
     public GameObject Grass_North;
     public GameObject Grass_South;
     public GameObject Grass_East;
     public GameObject Grass_West;
     public GameObject Grass_NorthEast;
     public GameObject Grass_NorthWest;
     public GameObject Grass_SouthEast;
     public GameObject Grass_SouthWest;
     public GameObject Grass_Middle;
 
     public GameObject currentLand;
 
 
     private void Start()
     {
 
             CreateLand();
       
            
     }
     public static void GetNeighbours_NorthAndSouth(CubeCell north, CubeCell south) 
     {
         north.west = south;
         south.east = north;
     }
 
     public static void GetNeighbours_EastAndWest(CubeCell east, CubeCell west)
     {
         east.south = west;
         west.north = east;
     }
 
     void CreateLand() 
     {
         Vector3 position = new Vector3(0,0,0);
 
         if(north == null && east == null) { currentLand = Grass_NorthEast; } else { currentLand = Grass_Middle; }
         GameObject newLand = Instantiate<GameObject>(currentLand);
         newLand.transform.localPosition = position;
         newLand.transform.SetParent(transform, false);
     }
 
     public void DestroyObject() 
     {
         GameObject.Destroy(gameObject);
     }
 }