title: Ransack on Gutentag tags- undefined method `type' for nil:NilClass
body: <p>Has anybody gotten Ransack to search Gutentag tag_names ? I have had issues making ActsAsTaggableOn work but Gutentag works like a charm, I just need to be able to search on it..</p>
  
  <p><code>resource.tag_names</code> returns a list of tags for <code>resource</code>.</p>
  
  <p>I have in my model</p>
  
  <pre><code>  def self.ransackable_attributes(auth_object = nil)
        ['title','content', 'tag_names']
    end
  </code></pre>
  
  <p>the line erroring is <code>@resources = @q.result(distinct: true).paginate(:page =&gt; params[:page])</code></p>
  
  <p>I'm assuming that tag_names is not returning the right data for Ransack. Any ideas?</p>