fix: Fix document not found bug in rfcdiff API (ietf-tools#6681)

Fixes ietf-tools#6675

Author: kesara

ietf/api/tests.py

@@ -1080,3 +1080,9 @@ def test_rfc_with_broken_history(self):
         # tricky draft names
         self.do_rfc_with_broken_history_test(draft_name='draft-gizmo-01')
         self.do_rfc_with_broken_history_test(draft_name='draft-oh-boy-what-a-draft-02-03')
+
+    def test_no_such_document(self):
+        for name in ['rfc0000', 'draft-ftei-oof-rab-00']:
+            url = urlreverse(self.target_view, kwargs={'name': name})
+            r = self.client.get(url)
+            self.assertEqual(r.status_code, 404)

ietf/api/views.py

@@ -327,7 +327,7 @@ def get_previous_url(name, rev=None):
 def rfcdiff_latest_json(request, name, rev=None):
     response = dict()
     condition, document, history, found_rev = find_doc_for_rfcdiff(name, rev)
-    if document.type_id == "rfc":
+    if document and document.type_id == "rfc":
         draft = document.came_from_draft()
     if condition == 'no such document':
         raise Http404