Error when trying to view jupyter notebooks changes via `View Unified`

Reproduction Instructions
Create a differential revision which removes/adds new block into jupyter notebook. View change as View Unified and it causes:

Argument 2 passed to PhabricatorJupyterDocumentEngine::newBlockContentView() must be an instance of PhabricatorDocumentEngineBlock, null given, called in <redacted> phabricator/src/applications/differential/render/DifferentialChangesetOneUpRenderer.php on line 380 and defined

or

Argument 2 passed to PhabricatorJupyterDocumentEngine::newBlockContentView() must be an instance of PhabricatorDocumentEngineBlock, null given, called in <redacted> phabricator/src/applications/differential/render/DifferentialChangesetOneUpRenderer.php on line 393 and defined

Line number changes depending if you add or delete jupyter notebook block.

Phabricator/Arcanist Version
Master

Thanks, should be fixed by https://secure.phabricator.com/D20897.