exception of empty cells now takes into account only the cells that c…

…an contain pieces

Match3Maker/src/components/Board.cs

@@ -243,9 +243,10 @@ public Board FillInitialBoard(bool allowMatchesOnStart = false, Dictionary<strin
                     }
                 }
 
-                if (EmptyCells().Count > 0)
+                if (EmptyCells().Where(cell => cell.CanContainPiece).Any())
                     throw new InvalidOperationException("Board->FillInitialBoard: After calling the function, some cells are still empty, the operation is not valid");
 
+
                 if (!allowMatchesOnStart && (preSelectedPieces is null || preSelectedPieces.IsEmpty()))
                     RemoveMatchesFromBoard();