When running arc diff --preview, visiting the diff URL produces the following error:
Unhandled Exception ("PhabricatorDataNotAttachedException")
Attempting to access attached data on DifferentialDiff (via getBuildable()), but the data is not actually attached. Before accessing attachable data on an object, you must load and attach it.
Data is normally attached by calling the corresponding needX() method on the Query class when the object is loaded. You can also call the corresponding attachX() method explicitly.
arc diff master --preview Linting... LINT OKAY No lint problems. Running unit tests... No unit test engine is configured for this project. SKIP STAGING No staging area is configured for this repository. Created a new Differential diff: Diff URI: https://phabricator.bloc.io/differential/diff/2839/ Included changes: M app/serializers/checkpoint_serializer.rb M app/views/checkpoints/_form.html.haml A db/migrate/20150811183024_update_extra_credit_checkpoints.rb M db/schema.rb
> arc --version arcanist 423e7d2389336430110f489e411fe0d66a25ade3 (11 Aug 2015) libphutil 6c0118085afdc6c6802849cac363efbc76def972 (11 Aug 2015)