activitypub transmogrifier: accept/reject outgoing: we might send the actual object instead of the URI in some cases, handle it

lib/pleroma/web/activity_pub/transmogrifier.ex

@@ -443,7 +443,14 @@ def prepare_outgoing(%{"type" => "Create", "object" => %{"type" => "Note"} = obj
   # Mastodon Accept/Reject requires a non-normalized object containing the actor URIs,
   # because of course it does.
   def prepare_outgoing(%{"type" => "Accept"} = data) do
-    with follow_activity <- Activity.get_by_ap_id(data["object"]) do
+    follow_activity_id =
+      if is_binary(data["object"]) do
+        data["object"]
+      else
+        data["object"]["id"]
+      end
+
+    with follow_activity <- Activity.get_by_ap_id(follow_activity_id) do
       object = %{
         "actor" => follow_activity.actor,
         "object" => follow_activity.data["object"],
@@ -461,7 +468,14 @@ def prepare_outgoing(%{"type" => "Accept"} = data) do
   end
 
   def prepare_outgoing(%{"type" => "Reject"} = data) do
-    with follow_activity <- Activity.get_by_ap_id(data["object"]) do
+    follow_activity_id =
+      if is_binary(data["object"]) do
+        data["object"]
+      else
+        data["object"]["id"]
+      end
+
+    with follow_activity <- Activity.get_by_ap_id(follow_activity_id) do
       object = %{
         "actor" => follow_activity.actor,
         "object" => follow_activity.data["object"],