Hammerspoon: Configure volume via keyboard shortcuts for macbook pro (touchbar, but no keys)

volume.lua

function changeVolume(diff)
  return function()
    local current = hs.audiodevice.defaultOutputDevice():volume()
    local new = math.min(100, math.max(0, math.floor(current + diff)))
    if new > 0 then
      hs.audiodevice.defaultOutputDevice():setMuted(false)
    end
    hs.alert.closeAll(0.0)
    hs.alert.show("Volume " .. new .. "%", {}, 0.5)
    hs.audiodevice.defaultOutputDevice():setVolume(new)
  end
end

hs.hotkey.bind({'ctrl', 'alt', 'cmd'}, 'Down', changeVolume(-3))
hs.hotkey.bind({'ctrl', 'alt', 'cmd'}, 'Up', changeVolume(3))

works for me under 10.15.4, with hammerspoon 0.9.78

every volume change also displays a popup for me... can you bind the keys to do sth else just for testing? or play around in the hammerspoon console?

Thanks so much Alexander for getting back to me so quickly.
I am on same mac and hammerspoon versions. very new on lua, not sure how to display debug msg in lua.
The wired part is, if I have click volumn icon on menu bar, volumn list is displayed, your hotkey works properly.

But I am in other application, use the hotkey, will not affect volumn at all

Thanks so much

works perfectly on my mechine, macOS 13.3.1, Hammerspoon 0.9.100.