LogicException error

I'm on Drupal 8.6.2 and seeing the following error when trying to use this module.

LogicException: The controller must return a response (null given). Did you forget to add a return statement somewhere in your controller? in Symfony\Component\HttpKernel\HttpKernel->handleRaw() (line 169 of /Users/anthonyfuentes/Development/Dev_Desktop/iqairdrupal8-test/docroot/vendor/symfony/http-kernel/HttpKernel.php).

Any ideas what this could be related to? I was referred to this module from here: https://drupal.stackexchange.com/questions/273840/view-using-path?noredi....