xeus-kernels fail

[DerThorsten]

all xeus kernels fail with the same error as jupyterlite/xeus-sqlite-kernel#10.

Interestingly I can locally install all of them via pip and they work without that issue

[DerThorsten]

@jtpio when I install all extensions locally (as in the requirements) I can reproduce the error locally...so...lets figure out which one is the bad one

[DerThorsten]

it sems that the xeus kernels atm dont work when ipywidgets is installed

[jtpio]

@DerThorsten the SQLite kernel seems to be working (when opening https://jupyterlite.github.io/demo/lab/index.html in a private window):

But after a kernel restart.

it sems that the xeus kernels atm dont work when ipywidgets is installed

You mean when the ipywidgets Python package is installed as part of the deployment? Or when the xeus kernels are compiled with widgets.

[martinRenou]

This issue is coming from xeus which complains about a non-existing comm target, and lamentably fails to show the error message. We fixed it very recently in https://github.com/jupyter-xeus/xeus/pull/327/files. Maybe we are not using that fix yet

[martinRenou]

Just to give more context about this error, https://github.com/jupyter-xeus/xeus/pull/327/files#diff-af1c39110d53dd864ae63b152634851fb7b89dbb43a93584ecd368db8414e9c2L90 is trying to concatenate an std::string with a fixed_string<64> resulting in a fixed_string<64> that is more than 64 characters, which makes a static assert fail.

[martinRenou]

I think the reason why you are not able to reproduce locally @DerThorsten is because you don't have the ipywidgets labextension in the page, so the front-end is not requesting the kernel for comm targets.

[martinRenou]

This should fix it jupyterlite/xeus-sqlite-kernel#11