esp8266 & ws2812 lua script hangs after the http request - lua

Question

I have written a LUA script whereby the color of the ws2812 changes when I call a url.
It is so that the ESP hangs when you first call the URL (http://IPADDRESS/?color=green&key=rpi). The color will be switched, but after that depends the ESP.
I've tried a lot. I do not know how to solve my problem. Connected is the PixelRing (ws2812) to D4 (gpio2).
Do you have a solution idea?
local SSID = "*******"
local SSID_PASSWORD = "******"
LED_COUNT = 12
SECRET_KEY = "rpi"
local buffer = nil
--ws2812.init()
function wait_for_wifi_conn ( )
tmr.alarm (1, 1000, 1, function ( )
if wifi.sta.getip ( ) == nil then
print ("Waiting for Wifi connection")
else
tmr.stop (1)
print ("ESP8266 mode is: " .. wifi.getmode ( ))
print ("The module MAC address is: " .. wifi.ap.getmac ( ))
print ("Config done, IP is " .. wifi.sta.getip ( ))
ws2812.init()
buffer = ws2812.newBuffer(LED_COUNT, 3)
end
end)
end
function connect(conn)
print("c2", conn);
conn:on ("receive",
function (cn, req_data)
if req_data:find('^GET /.* HTTP/1.1') ~= nil then
local key = string.match(req_data, "key=(%a+)")
local color = string.match(req_data, "color=(%a+)")
if key == SECRET_KEY then
local r, g, b = nil, nil, nil
if color == "red" then
r = 255
g = 0
b = 0
elseif color == "blue" then
r = 0
g = 0
b = 255
elseif color == "green" then
r = 0
g = 255
b = 0
end
if r ~= nil then
tmr.alarm(2, 100, tmr.ALARM_SINGLE, function()
--buffer = ws2812.newBuffer(LED_COUNT, 3);
buffer:fill(g,r,b); -- grb not rgb
print(buffer)
--ws2812.init()
ws2812.write(nil, buffer)
end)
end
end
end
-- Close the connection for the request
cn:on("sent",function(c) print("c0", c);c:close() end)
cn:send("<h1> Hello, NodeMcu.</h1>")
-- Close the connection for the request
--cn:on("sent",function(cnn) cnn:close() end)
end)
--conn:send("<h1> Hello, NodeMcu.</h1>")
end
wifi.setmode(wifi.STATION)
wifi.sta.config {ssid=SSID, pwd=SSID_PASSWORD}
wifi.sta.autoconnect(1)
wait_for_wifi_conn()
svr = net.createServer(net.TCP, 30)
if svr then
svr:listen (80, connect)
end
Thanks for Help =)