Recently, I have updated to the latest [1.5] release of this module and I hav...

Recently, I have updated to the latest [1.5] release of this module and I have also faced the same issue of cookies being undefined error.
However, if you go to the autologout.libraries.yml file, you can see it is dependent on the libraries of [https://www.drupal.org/project/js_cookie] module.
You can install and enable the module and the cookie_undefined error will be resolved.