attempt to index upvalue 'shell' (a userdata value)

[forever403]

local shell = require "resty.shell"
ngx.req.read_body()
local args = ngx.req.get_post_args()

shell.run("/bin/echo", args.name)

[forever403]

nginx version is 1.19.4 ，the same code can run on nginx 1.17.7