If you’re using a model or controller from an engine in Rails 2.3.2 you may encounter some crazy errors from time to time. Errors like: A copy of ApplicationController has been removed from the module tree but is still active! Or sometimes the even weirder one: can't dup NilClass In one situation where you get A copy of ApplicationController has been removed from the module tree but is still activ
![Can't dup NilClass… maybe try `unloadable`](https://cdn-ak-scissors.b.st-hatena.com/image/square/1213c249cd3981c5775abc9715f96cd2449537af/height=288;version=1;width=512/https%3A%2F%2Fblog.danielx.net%2Fwp-content%2Fuploads%2F2019%2F12%2Fcropped-disco.png%3Fw%3D200)