After upgrading lua resty core to 0.1.17 for every request seeing some warnings related to race condition

Getting below error:
[warn] 5352#5352: *290 [lua] _G write guard:12: __newindex(): writing a global lua variable ('message') which may lead to race conditions between concurrent requests, so prefer the use of 'local' variables

Sample code
local M = {}
local function checkAuth()

-- logic to get auth value
if type(check[auth.type]) == "function" then
ok, message = checkauth.type
if ok then
authorized= true
break
end
end
-- logic
end
M.checkAuth=checkAuth
return M

Corresponding Nginx version : nginx-plus-20-1.el7.ngx.x86_64
Before upgrading Nginx version and lua-resty-core I didn't see any such errors

Start with the _G write guard warning and the sample checkAuth function, focusing on the undeclared message assignment and the nginx-plus-20/lua-resty-core upgrade context. Reproduce the warning with the sample request flow and compare behavior before and after the upgrade. Done means establishing whether the warning is expected for this code and identifying the affected change or documentation needed.