Diff is (sometimes) not updated even after closing and re-opening

Description

After certain sequence of events that I cannot reproduce yet the notebook diff stops updating. The old/partial/incorrect (not sure which) diff is shown instead. No error is shown to the user.

Reproduce

In the diff there are SVG outputs and code cells.

I have not found a way to reproduce this yet. Roughly it could be something like:

• modify a tracked notebook
• added to staging area
• diff
• close diff
• modify again
• diff
• see the old/partial/incorrect diff
• see in network requests in developer tools that diffnotebook? correctly downloads the updated diff but it is not being displayed
• see captured nbdime error:

Failed to init notebook diff view: Error: Invalid arguments to createDirectStringDiffModel(). Both base and remote cannot be equal!

When I tried to diff that notebook using nbdime button directly:

Uncaught (in promise) Error: Invalid arguments to createDirectStringDiffModel(). Both base and remote cannot be equal!
    at Object.t.createDirectStringDiffModel (568.aa5ce6fc20353381fe5b.js?v=aa5ce6fc20353381fe5b:1)
    at stringify (568.aa5ce6fc20353381fe5b.js?v=aa5ce6fc20353381fe5b:1)
    at stringify (568.aa5ce6fc20353381fe5b.js?v=aa5ce6fc20353381fe5b:1)
    at m.createOutputTextView (568.aa5ce6fc20353381fe5b.js?v=aa5ce6fc20353381fe5b:1)
    at m.createView (568.aa5ce6fc20353381fe5b.js?v=aa5ce6fc20353381fe5b:1)
    at new m (568.aa5ce6fc20353381fe5b.js?v=aa5ce6fc20353381fe5b:1)
    at Function.createView (568.aa5ce6fc20353381fe5b.js?v=aa5ce6fc20353381fe5b:1)
    at h.init (568.aa5ce6fc20353381fe5b.js?v=aa5ce6fc20353381fe5b:1)
    at new h (568.aa5ce6fc20353381fe5b.js?v=aa5ce6fc20353381fe5b:1)
    at 568.aa5ce6fc20353381fe5b.js?v=aa5ce6fc20353381fe5b:1

Expected behavior

The diff should get updated; if diff cannot get updated to the new one full an error should be shown to the users to that:

• they are not shown incorrect diff (which is misleading and dangerous)
• they can report this here with more details so we can solve it

Context

JupyterLab: 3.0.15

• Python package version: 0.30
• Git version: 2.31
• Operating System and its version: Ubuntu 21.04

[fcollonval]

Is there a way to enable source map for extensions easily (without installing the dev version)? It seems to work for core packages.

With federated module, I think the only possibility is to install nbdime in dev mode as maps are not part of the distributed package files.

[fcollonval]

Thanks @vidartf - closing this one.