Fix activities failing to render because the object is a user/unavailable

lib/pleroma/web/activity_pub/views/object_view.ex

@@ -30,9 +30,14 @@ defmodule Pleroma.Web.ActivityPub.ObjectView do
     base = Pleroma.Web.ActivityPub.Utils.make_json_ld_header()
     object = Object.normalize(activity)
 
+    additional = Transmogrifier.prepare_object(activity.data)
+
     additional =
-      Transmogrifier.prepare_object(activity.data)
-      |> Map.put("object", object.data["id"])
+      unless is_nil(object) do
+        Map.put(additional, "object", object.data["id"])
+      else
+        additional
+      end
 
     Map.merge(base, additional)
   end

test/web/activity_pub/views/object_view_test.exs

@@ -55,4 +55,13 @@ defmodule Pleroma.Web.ActivityPub.ObjectViewTest do
     assert result["object"] == note.data["object"]["id"]
     assert result["type"] == "Announce"
   end
+
+  test "renders an activity with a user as an object/nonexistent object" do
+    user = insert(:user)
+    other_user = insert(:user)
+
+    {:ok, _user, other_user, activity} = CommonAPI.follow(user, other_user)
+    result = ObjectView.render("object.json", %{object: activity})
+    assert result["object"] == other_user.ap_id
+  end
 end