Unity freezes on play, if a script tries to edit Arrays

I started to make a Minesweeper game for fun, but for some reason, editing arrays doesn't seem to work at all. If I include the code in a script, attach it to an object, then when I click on play, Unity completely freezes and I have to kill the process from the Task Manager.

The code:*

 var TotalTiles = 81;        // Total number of tiles on the current board
 var RandomNumber : int;
 var MineArray : int[];        // Array of all mines
 var TotalMines = 10;        // Total number of mines
 
 var restart = false;
 
 function SetMines()
 {
     // Set all 10 mines using a loop
 
     for ( var index = 0; index < TotalMines;)
     {
         restart = false;
 
         // Select a random tile with Random.Range returning a number
         // between 1.0 and 81.99 and converting it to an int.
 
         // Since each tile is numbered ( from 1 to 81 ); the Random number
         // will be the "ID" of the tile, the current mine will be hidden in.
 
         RandomNumber = Random.Range( 1.0, TotalTiles + 0.99 );
         
         // Check if any of the previous mines has the same ID as the current one,
         
         for ( var i = 0; i < index; )
         {
         
             // if there is, reset everything and start the loop again
         
             if ( MineArray[i] == RandomNumber )
             {
                 restart = true;
                 i = 0;
                 break;
             }
             
             // if there is not, continue until it has checked every mine
             
             else
             {
                 i += 1;            
             }
         }
         if ( restart == true )
         {
             continue;
         }
         
         // After all mines are checked, assign the ID to the current mine,
         // and store in in MineArray at the current index, then continue the loop
         
         else
         {
             MineArray[index] = RandomNumber;
             if ( index < TotalMines )
             { 
                 index += 1;
                 continue;
             }
             else
             { break; }
         }
     }
 }

Any ideas why this doesn't work?

Thanks