title: Preview custom 500 error page in Wagtail?
body: <p>I've made custom 500 and 404 error pages in Wagtail. I can preview the 404 page by typing in a false url. I'm just wondering how I can preview the 500 page? </p>
  
  <p>The custom page has links to static images that I need to check are working.</p>
  
  <p>My urls.py</p>
  
  <pre><code>from django.conf import settings
  from django.conf.urls import include, url
  from django.conf.urls.static import static
  from django.contrib import admin
  
  from wagtail.contrib.sitemaps.views import sitemap
  from wagtail.admin import urls as wagtailadmin_urls
  from wagtail.core import urls as wagtail_urls
  from wagtail.documents import urls as wagtaildocs_urls
  
  
  admin.autodiscover()
  
  urlpatterns = [
      url(r'django-admin/', admin.site.urls),
  
      url(r'^admin/', include(wagtailadmin_urls)),
      url(r'^documents/', include(wagtaildocs_urls)),
  
      url(r'^sitemap\.xml$', sitemap),
  
      url(r'', include('puput.urls')),
      url(r'', include(wagtail_urls)),
  ]
  
  urlpatterns += static(settings.MEDIA_URL, document_root=settings.MEDIA_ROOT)
  
  if 'debug_toolbar' in settings.INSTALLED_APPS:
      import debug_toolbar
  
      urlpatterns += [
          url(r'^__debug__/', include(debug_toolbar.urls)),
      ]
  </code></pre>