Add cell and notebook properties to the JupyterError event

[cmarmo]

Dear maintainers,
this pull request adds the id and metadata cell properties to the JupyterError event schema and to the reported metrics.

Thank you for considering it.

[nthiery]

Hello,
Just asking a question at random, as I don't know the details of how cells are stored in memory.

Does cell.model.toJSON() triggers a full copy of all the data in the model?

If yes, then performance could be improved by:

• calling cell.model.toJSON() only once
• if possible: calling toJSON() selectively on the specific metadata attributes that will be exploited

Motivation: some of the cell metadata attributes may have large values, like for widget states. The model itself might (?) contain large data, like cell outputs).

[afshin]

Yes, cell.model.toJSON() serializes completely. for id this is superfluous because id is always a primitive. For metadata it makes sense because it's better to make a copy than to pass by reference. But @cmarmo, I would ask, do you actually want everything inside metadata? Depending on the notebook this might have fields you don't care about. Either way, @nthiery's point is valid.

[cmarmo]

Thanks @afshin for your answer: in general I don't want to keep all the metadata, but the extension we are using now is configurable, so we can choose a list of metadata to be kept.
I wonder whether it is relevant to implement all the selection and configuration machinery here or create a new extension based on this one with custom events.

[afshin]

Well, we already know all metadata is safe json and we can't seek out specifics within that metadata at this layer of the stack, so I think your plan to emit the whole of the cell's metadata is okay here.

[afshin]

I would define the things you want JupyterError to provide under the cell key instead of making just a plain JSON object. It'll make it clearer what the emission is shipping.

[afshin]

You're on the right track here! The build only failed because it needs a jlpm lint to catch linting issues.

[cmarmo]

I believe I have addressed the comments.
Also I have tentatively added "notebook" among the recorded information, hoping to retrieve the name/path of the executed notebook. I only have the id for now as I am unable to retrieve the path property without adding a NotebookTracker: is there another way?