Index out of range, cant find error

Hi all!

I have a simple script in c# to generate world tiles, but when i try to run it it gaves me an index out of range error, here is my script.

 using UnityEngine;
 using System.Collections;

 public class Tilemap : MonoBehaviour {
 
 
     public TileType[] tileTypes;
 
     int[,] tiles;
 
     int mapSizeX = 10;
     int mapSizeY = 10;
 
     void Start()
     {
         // Allocate our map tiles
         tiles = new int[mapSizeX,mapSizeY];
 
         //Initialize our map tiles.
         for (int x=0; x<mapSizeX; x++)
         {
             for (int y = 0; y < mapSizeY; y++)
             {
                 tiles[x,y] = 0;
             }
   
         }
             
         GenerateMapVisual();
 
 
 
     }
 
 
 
 
     void GenerateMapVisual()
     {
         for (int x = 0; x < mapSizeX; x++)
         {
             for (int y = 0; y < mapSizeY; y++)
             {
 

//Here is the error shown, i tried without this line with a debug.log and it works, so the error must be in this line (below)

                 *TileType tt = tileTypes[ tiles[x,y] ];*

                 Instantiate(tt.tileVisual, new Vector3(x, y, 0), Quaternion.identity);
 
 
             }
 
         }
 
     }
 
 }