Getting GameObject from a grid (array) using raycasters

So I have an array of GameObjects that is created when the game is started using the following code:

 void Awake () {
         for (int x = 0; x < width; x++) {
             for (int z = 0; z < height; z++) {
                 GameObject grid = (GameObject)Instantiate(gridPiece);
                 grid.transform.position = new Vector3(gridPiece.transform.position.x - x, 0, gridPiece.transform.position.z + z);
                 grid.transform.parent = gameObject.transform;
             }
         }
     }

When I press play GameObjects are spawned as expected in a grid over a plane. I want to get the GameObject that the mouse is over. To do that I'm using raycasts:

 void Update () {
         Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
         RaycastHit hit;
         // Casts the ray and get the first game object hit
         Physics.Raycast(ray, out hit);
         Debug.Log("This hit at " + hit.point);
     }

I then plan to use this to get the GameObject:

 private Vector3 getNearestPoint(Vector3 _point){
         int x = Mathf.RoundToInt (_point.x);
         int y = Mathf.RoundToInt (_point.y);
         int z = Mathf.RoundToInt (_point.z);
 
         Vector3 nearestPoint = new Vector3(x,y,z);
 
         return nearestPoint;
     }
 
     private GameObject objectFromPosition(Vector3 _point){
         int x = (int)_point.x;
         int z = (int)_point.z;
 
         GameObject tile = grid[x,z];
         return tile;

     }

However I'm getting an error saying that array index is out of bounds for GameObject tile = grid[x,z];

If anyone has any ideas as to why this might be, or how I might be able to achieve the same goal in a better way, that'd be greatly appreciated. Thanks!