Clean - AI movement

    // To perform every tick
    public override void MovementTick()
    {
       GridObject lowestCostObject = aiFinder.LowestCostObject();
       Tile targetTile = lowestCostObject.currentTile;
       currentTilePath = pathfinding.FindPath(headBody.gridObject.currentTile, targetTile);

       if (currentTilePath != null)
       {
           MoveHeadToTile(currentTilePath[0]);
           return;
       }

       // If can't find an object, it will try to move to a random valid neighbour
       Tile randomValidTile = RandomValidTile();
       if (randomValidTile == null)
       {
           // Move up and die if there's no valid neighbours
           MoveHeadToTile(headBody.gridObject.currentTile.neighbourTiles[(int)Direction.Up]);
           return;
       }
       // Move to random tile if path wasn't found
       MoveHeadToTile(randomValidTile);
   }