ffizlib.deflateGzip 浏览器访问没问题，安卓okhttp访问报错500

lua中使用ffizlib，浏览器访问没问题，安卓okhttp访问报错500，代码如下

local chunk =16384 --#resbody

ngx_log(ngx_INFO,"chunk:",chunk)

local count = 0

local input = function(bufsize)

local start = count > 0 and bufsize*count or 1

local data = "" (bufsize*(count+1)-1))

if data == "" then

data = "">

end

count = count + 1

return data

end

local output_table = {}

local output = function(data)

table_insert(output_table, data)

end

ngx_log(ngx_INFO,"ffizlib.deflateGzip start")

local ok, err = ffizlib.deflateGzip(input, output, chunk)

报错信息：

attempt to call global 'table_insert' (a nil value)，上面代码的output部分。