Hammerspoon does not respond/hang when the frontmost application does not respond

[NightMachinery]

Hammerspoon does not respond/hang when the frontmost application does not respond. I notice this most frequently with emacs, as emacs has terrible concurrency and does not respond to new events whenever it is doing sth heavy. This makes hammerspoon also not respond, which is terrible.

I have the following elisp code which "simulates" a hanged emacs:

(defun night/busy-spin (&optional duration)
  "Busy spin for DURATION seconds."
  (interactive "nDuration (seconds): ")
  (let ((end-time (time-add (current-time) (seconds-to-time (or duration 30)))))
    (while (time-less-p (current-time) end-time)
      ;; Do nothing except consume CPU cycles.
      )))

(night/busy-spin 20)

Using this, the code that causes Hammerspoon to hang seems to be this:

function toggleFocus(appName)
    local launch_p = false

    local app = nil
    app = hs.application.get(appName)

    if app then
        if app:isFrontmost() then
            app:hide()
        else
            app:activate()
        end
    else
        if launch_p then
            hs.application.launchOrFocus(appName)
            app = hs.application.get(appName)
        end
    end
end

When toggleFocus("org.gnu.Emacs") is run and emacs is hanged, Hammerspoon will hang.

How do I solve this?