joestump/django-ajax — pull request #19 by rmaceissoft (2011-12-16 18:12:54+00:00)
Title: catched Http404 exception type and return AjaxError response with 404 code

It's very common use **get_object_or_404** or **get_list_or_404** shortcuts when you are implementing ajax endpoint, similar when you are implementing django view.

so, I don't see a reason to send to cliente http 500 error.