SSUI-conky script problem

Hello,
I have a problem when running a conky script I have this error:

modules/weather/scripts/fetch-weather.lua:71: attempt to index a nil value (field 'main')

here is the portion of the script:

    if file_exists(cache_file) then
        cache = io.open(cache_file,"r+")
        data = json.decode(cache:read())
        timepassed = os.difftime(currenttime, data.timestamp)
    else
        cache = io.open(cache_file, "w")
        timepassed = 6000
    end

    makecache = function (s)
        s.timestamp = currenttime
        save = json.encode(s)
        cache:write(save)
    end

    if timepassed < 3600 then
        response = data
    else
        weather = http.request(("%sid=%s&units=%s&APPID=%s"):format(api_url, cityid, cf, apikey))
        if weather then
            response = json.decode(weather)
            makecache(response)
        else
            response = data
        end
    end

    math.round = function (n)
        return math.floor(n + 0.5)
    end

    temp = response.main.temp    <----- error here 
    conditions = response.weather[1].main
    icon = response.weather[1].icon:sub(1, 2)