Only send balls when not sending lines

src/main.cpp

@@ -30,10 +30,11 @@ websockets::TestProtocol<User> default_protocol{
 	// write (will always come after receive)
 	[](User& user, basic_websocket_info) -> std::string{
 		js::Object ret;
-		ret["balls"] = vector_to_json(app->sim.balls, [](ball_type const & b){return cheap_ball_type(b);});
 		if(user.update_lines){
 			ret["lines"] = vector_to_json(app->lines, [](AbstractLine const & l){return cheap_line_type(l);});
 			user.update_lines = false;
+		} else {
+			ret["balls"] = vector_to_json(app->sim.balls, [](ball_type const & b){return cheap_ball_type(b);});
 		}
 		return write_json(ret);
 	},