Runtime error when using with OpenResty

[vsajip]

I'm getting an error using htaccess.lua with openresty/1.21.4.1 under the following circumstances:

• I'm using the latest htaccess.lua from this repository. I've placed it in /usr/local/openresty/nginx/scripts.

• I have a directory, /usr/local/openresty/nginx/html/protected, which I'm trying to protect using .htaccess.

• The .htaccess file ( /usr/local/openresty/nginx/html/protected/.htaccess) contents are:

	AuthType Basic
	AuthName "Restricted Content"
	AuthUserFile .htpasswd
	Require valid-user

• The nginx configuration (relevant portions) are:

http {
	...
	lua_shared_dict htaccess 4m;
	...
}

server {
	...
	rewrite_by_lua_file /usr/local/openresty/nginx/scripts/htaccess.lua;
	...

        location / {
            root   html;
            index  index.html index.htm;
        }
	...
}

When the rewrite_by_lua_file line is commented out, I can access content in /protected, as expected. When not commented out, access to /protected/index.html leads to a Lua runtime error:

2023/05/30 09:15:43 [error] 18532#18532: *17 lua entry thread aborted: runtime error: /usr/local/openresty/nginx/scripts/htaccess.lua:119: attempt to concatenate global 'doc_root' (a nil value)
stack traceback:
coroutine 0:
        /usr/local/openresty/nginx/scripts/htaccess.lua: in function 'ensure_doc_root'
        /usr/local/openresty/nginx/scripts/htaccess.lua:145: in function 'get_file_contents'
        /usr/local/openresty/nginx/scripts/htaccess.lua:507: in function 'parse_htaccess_directive'
        /usr/local/openresty/nginx/scripts/htaccess.lua:1012: in main chunk, client: 146.90.194.232, server: foo.bar.com, request: "GET /protected/index.html HTTP/2.0", host: "foo.bar.com"

Any idea what could be the cause of the problem? It seems like in https://github.com/e404/htaccess-for-nginx/blob/b81c1f1a4573839021284652c75e2a42d008d72a/htaccess.lua#L114-L118 there's a reference to doc_root, which is not defined globally and is local to in_doc_root.