Only try to render resolved links

apps/navigation/widgets.py

@@ -24,6 +24,7 @@ def button_navigation_widget(request, link):
 def render_widget(request, link):
     context = RequestContext(request)
     resolved_link = link.resolve(context)
+    if resolved_link:
         return mark_safe(u'<a style="text-decoration:none; margin-right: 10px;" href="%(url)s"><button style="vertical-align: top; padding: 1px; width: 110px; height: 100px; margin: 10px;"><img src="%(static_url)simages/icons/%(icon)s" alt="%(image_alt)s" /><p style="margin: 0px 0px 0px 0px;">%(string)s</p></button></a>' % {
             'url': resolved_link.url,
             'icon': getattr(resolved_link, 'icon', 'link_button.png'),
@@ -31,3 +32,5 @@ def render_widget(request, link):
             'string': capfirst(resolved_link.text),
             'image_alt': _(u'icon'),
         })
+    else:
+        return u''