Trying to submit a diff via `arc diff`. Getting the following error:
```
Exception
ERR-CONDUIT-CORE: Argument 2 passed to HeraldDifferentialRevisionAdapter::newLegacyAdapter() must be an instance of DifferentialDiff, null given, called in /core/lib/phabricator/src/applications/differential/editor/DifferentialTransactionEditor.php on line 1585 and defined
```