hammerspoon: `application.watcher` stops watching after several times

With release 0.9.43 I am testing the application.watcher. Depending on complexity/load of the init script, the watcher stops after several executions, hammerspoon still keeps on listening to e.g. keyboard bindings.

Down, an applescript and an init.lua is appended to reproduce the issue. With my personal configuration the watcher stops is after 10 times switching applications. The problem occurs with the appended scripts after 400 times switching applications (yes 40 seconds to reproduce the bug).

-- applescript
repeat 100 times
    tell application "System Events"
        delay 0.1
        key code 48 using command down -- send cmd + tab
    end tell
end repeat

-- init.lua
hs.application.watcher.new(function(name,event, app) appwatch(name,event,app) end):start()

local i = 1
function appwatch(name, event, app)
  local win = hs.window.focusedWindow()
  if not win then
    print("no window focused")
    return
  end

  local lookuptable = {
    [hs.application.watcher.activated] = "act",
    [hs.application.watcher.deactivated] = "deact",
    [hs.application.watcher.hidden] = "hid",
    [hs.application.watcher.launched] = "lnchd",
    [hs.application.watcher.launching] = "lnchng",
    [hs.application.watcher.terminated] = "term",
    [hs.application.watcher.unhidden] = "unhid"
  }
  print(i .. " event: ".. lookuptable[event] .. "; app: " .. hs.window.focusedWindow():application():title())
  if event == hs.application.watcher.activated then
    i = i+1
  end
end