activitypub.actor bug fix: handle opted out users

fixes https://console.cloud.google.com/errors/detail/CKOs59zx0rSXQg;time=P30D?project=bridgy-federated

activitypub.py

@@ -797,6 +797,9 @@ def actor(handle_or_id):
 
     assert id
     user = cls.get_or_create(id)
+    if not user:
+        error(f'{cls.LABEL} user {id} not found', status=404)
+
     if not user.obj or not user.obj.as1:
         user.obj = cls.load(user.profile_id(), gateway=True)
         if user.obj:

tests/test_activitypub.py

@@ -461,6 +461,14 @@ class ActivityPubTest(TestCase):
             self.assertEqual(301, resp.status_code)
             self.assertEqual('https://fed.brid.gy/user.com', resp.headers['Location'])
 
+    def test_actor_opted_out(self, *_):
+        self.user.obj.our_as1['summary'] = '#nobridge'
+        self.user.obj.put()
+        self.user.put()
+
+        got = self.client.get('/user.com')
+        self.assertEqual(404, got.status_code)
+
     def test_individual_inbox_no_user(self, mock_head, mock_get, mock_post):
         self.user.key.delete()