Why ReloadUI() method causes mistake

[blocker147]

I'm trying to call ReloadUI() method after one minute. This is code I'm using.

local isEnd = false

local f = CreateFrame("Frame")
function f:onUpdate(sinceLastUpdate)
   if isEnd then
      print("END")
      f:SetScript("OnUpdate",nil)
      ReloadUI()
   end
   
   self.sinceLastUpdate = (self.sinceLastUpdate or 0) + sinceLastUpdate
   if ( self.sinceLastUpdate >= 60 ) then -- in seconds
      -- do stuff here
      print("MSG")
      self.sinceLastUpdate = 0
      isEnd = true
   end
end
f:SetScript("OnUpdate",f.onUpdate)

When the minute passes I get an error:

How to fix this? Or any ideas how to make one minute delay?
I found other function on https://wowwiki.fandom.com/wiki/USERAPI_wait

 <PREFIX>_wait(delay, func [, param [,param [,...]]])

But I don't understand how to use it. What is <PREFIX>? And code example on same link not working.