why?

    public String play() {
        System.err.println(neighbours.get(position));
        for (Point p : neighbours.get(position)) { // position is not null
            if (!visited.contains(p)) {
                System.err.println(p); //p is not null
                return moveTo(map.pointToDirection(position,p)); // nullpointerexception, can't call the function pointToDirection
            }
        }
        return surface();
    }