Request for help in interpreting a diagnostic message from ipywidgets (KeyError)

[mprogram]

It's rather a question, not an issue:

With the help of kernelspy upon running various examples (animations in pythreejs, etc., namely, when rendering a core functional part of a corresponding widget)* I'm getting this kind of a diagnostic message:

0: "---------------------------------------------------------------------------"
1: "KeyError Traceback (most recent call last)"
2: "/usr/lib/python3/dist-packages/ipywidgets/widgets/widget.py in _handle_msg(self, msg) 660 """Called when a msg is received from the front-end""" 661 data = msg['content']['data'] --> 662 method = data['method'] 663 664 if method == 'update': "
3: "KeyError: 'method'"

How should I interpret it in simple terms? Thank you in advance.
*. JupyterLab 0.33.6 and ipywidgets 7.3.1

[jasongrout]

Do you have a simple self-contained example reproducing the issue?

[jasongrout]

It seems that the kernel side is not getting a correctly-formed message from the javascript.

[mprogram]

Yes, it's a continuation of issue(s) no. 206 on pythreejs, nos. 14 and 13 on ipywebrtc, and no 159 on ipyvolume. I've seen a similar message referenced by me in pull request no. 661 on bqplot.

[mprogram]

I've just posted a detailed investigation on the pythree issues. Please, have a look there.

[mprogram]

No longer the issue after various upgrades, closing.

[jasongrout]

Great, thanks for following up here. I'm glad it's working for you now.