title: ActiveAdmin: How to override index controller action: undefined method `base' for nil:NilClass
body: <p>I'm trying to override the index action of the ActiveAdmin controller for it to display results for the current_user instead of all results.</p>
  
  <pre><code>controller do
    def index
      @user_tasks = UserTask.where(:user_id =&gt; current_user.id).page(params[:page])
    end
  end
  </code></pre>
  
  <p>When accessing ActiveAdmin, an exception in thrown:</p>
  
  <pre><code>ActionView::Template::Error (undefined method `base' for nil:NilClass):
      1: render renderer_for(:index)
  </code></pre>
  
  <p>I'm using rails 3.1 and the latest ActiveAdmin version. <code>gem "activeadmin", :git =&gt; 'https://github.com/gregbell/active_admin.git'</code>.</p>