title: Django template ValueError The 'image' attribute has no file associated with it
body: <p>I have context information sent to this part of the view. Have a paginator and works well for pages 1-3. But going to page four it has this error.</p>
  <blockquote>
  <p>Exception Type: ValueError</p>
  <p>Exception Value: The 'image' attribute has no file associated with it.</p>
  </blockquote>
  <p>The error in the template is highlighted by django debug as</p>
  <blockquote>
  <p>Error during template rendering</p>
  </blockquote>
  <p>In template <code>/templates/marketplace/entry_list.html</code>, error at line 91:</p>
  <blockquote>
  <p>The 'image' attribute has no file associated with it.</p>
  </blockquote>
  <pre><code>&lt;a href=&quot;{{ e.get_absolute_url }}&quot; title=&quot;{{ e.title }}&quot;&gt;
      {% if e.picture.url %}
          {% thumbnail e.picture &quot;300x600&quot; as thumb %}
              &lt;img src=&quot;{{ thumb.url }}&quot; alt=&quot;{{ e.title }}&quot; /&gt;
          {% endthumbnail %}
      {% endif %}
  &lt;/a&gt;
  </code></pre>
  <p>The part of the view sending context info is as below</p>
  <pre><code>get_context_data(self, **kwargs):
      if self.request.mobile:
          self.template_name = 'mobile/buy_n_sell.html'
      
      today = datetime.date.today()
      context = super(EntryList, self).get_context_data(**kwargs)
      context['category'] = self.category
      try:
          children = self.category.get_child_categories()
      except:
          children = None
      context['child_category'] = children
      context['area'] = self.area
      return context
  </code></pre>