RuntimeError: I've made a huge mistake

Check full details on Airbrake: https://huckleberry.airbrake.io/groups/61515161?auth_token=48d6bc457fadea0686842516b24d3b2b886c563d

```
/testapp/app/models/user.rb:53:in `public'
/testapp/app/controllers/users_controller.rb:14:in `index'
```
