Вопрос Weave help

[SewqPL]

ui.add_checkbox('[Visual] Menu alpha', 'indlist')
ui.add_slider("[Menu] alpha", "mealpha", 0, 255);

function kind(){
    var on = vars.get_int("js.indlist")
    var menuopen = ui.is_menu_down()
    if(menuopen){
        if(on){
            var bda = vars.get_int("js.mealpha")
            var screen = render.get_screen_size()
            var x = 0;
            var y = 0;
    
            render.filled_rect([x, y ], [screen[0], screen[1]], [0, 0, 0, bda], 0);
    
        }
    }
}
register_callback("render", kind)

can anyone tell me why i have [weave] JavaScript: Callback failed: 'TypeError: undefined not callable (property 'is_menu_down' of [object Object])' in javascript?