Remaining time or counter

[Tee_Trinker]

Hi guys, I'm using Erwin's script.
But recently I've been getting this error message in the script log.
I use the script to operate an EnOcean switching module. It sends a short button signal to my garage door opener.
Everything still works, only this error message is new.
What could it be?

Thanks for the help
David

Code:

-- ** Staircase logic with external time object and retriggering on input object Version 3.1 ** --
-- ****************************** Created by Erwin van der Zwart **************************** --
-- ************************************** SET PARAMETERS ************************************ --
-- Set input address
AddressInput = '32/1/80'
-- Set output address
AddressOutput = '32/1/71'
-- Set unique name for staircase timer (to avoid same storage name usage)
StaircaseName = 'PIR_TR2_1'
-- Set external time address (optional)
AddressExternalTime = '4'
-- Use time left indication
UseTimeLeft = false -- Set to true if time left indication will be used
-- Set feedback adress of time left indication (optional)
AddressTimeLeft = ''
-- Set time delay (Used when external time is not available)
SetDelay = 2
-- Seconds or Minutes
SetSec = true-- Set to false for Minutes
-- Set factor delay (Multiplies Delay)
SetFac = 2
-- Logic can be turned of by value 0
Off_by_Value_Zero = false
-- ************************************** END PARAMETERS ************************************ --
-- *************************** DON'T CHANGE ANYTHING UNDER THIS LINE ************************ --
inputvalue = event.getvalue
if Off_by_Value_Zero == false and (event.getvalue() == false or event.getvalue() == 0) then
  -- Exit script
  return
end
ValueInput = grp.getvalue(AddressInput)
ValueOutput = grp.getvalue(AddressOutput)
ValueExternalTime = grp.getvalue(AddressExternalTime)
if SetSec == true then
  SetSeconds = 1
else
  SetSeconds = 60
end
if ValueExternalTime == nil then
ValueExternalTime = 0
end
if ValueExternalTime > 0 then
  StairCaseTime = ValueExternalTime * SetSeconds * SetFac
else
  StairCaseTime = SetDelay * SetSeconds * SetFac
end
if ValueInput == true then
  --check for earlier started scrips
  --check storage for stpid value
  stpid = storage.get(StaircaseName) 
  --check if stpid has a value
  if stpid == nil then
    pid = os.getpid()
    storage.set(StaircaseName, pid)
  else
    -- kill earlier running script   
    os.kill(stpid, signal.SIGKILL)
    -- create new pid for next time to kill
    pid = os.getpid() 
    storage.set(StaircaseName, pid)
  end
  if ValueOutput == false then
    grp.write(AddressOutput, true)
    ValueOutput = true
  end
  -- Check time left indication is used
  if UseTimeLeft == true then
    if StairCaseTime > 0 then
        grp.update(AddressTimeLeft, StairCaseTime)
        repeat
          StairCaseTime = StairCaseTime - 1
          grp.update(AddressTimeLeft, StairCaseTime)
          os.sleep(1)
        until StairCaseTime == 0
    end   
  else
    os.sleep(StairCaseTime)
  end
  ValueOutput = grp.getvalue(AddressOutput)
  if ValueOutput == true then
    ValueInput = grp.getvalue(AddressInput)
    if ValueInput == true then
        grp.write(AddressInput, false)
      ValueInput = false
    end
    if Off_by_Value_Zero == false then
      if ValueOutput == true then
            grp.write(AddressOutput, false)
        ValueOutput = false
          end
    else
      -- Do nothing, this will trigger else condition below on next run
    end
  end 
else
  --check for earlier started scrips
  --check storage for stpid value
  stpid = storage.get(StaircaseName) 
  --check if stpid has a value
  if stpid == nil then
  else
    -- kill earlier running script   
    os.kill(stpid, signal.SIGKILL)
    grp.update(AddressTimeLeft, 0)
    pid = nil
    storage.set(StaircaseName, pid)
  end
  if ValueOutput == true then
    grp.write(AddressOutput, false)
  end
end