Error: Object 'jupyter.widget' not found in registry

[MariuszJurowicz]

[MariuszJurowicz]

Seams like the error is thrown when more than one notebook panels are opened.
There are more than one kernel started then and only one at the beginning has the jupyter.widgets extension registered.

[MariuszJurowicz]

After some debugging we discovered that this issue is caused by Lab source code.
This error is visible only when the Lab is opened with at least two notebooks.