Unable to access ipympl from JupyterLab due to Error displaying widget: model not found

[mtnt-2022]

Describe the issue

I am running an example code to access ipympl from Jupyter Lab on GCP/Linux.

%matplotlib widget
import matplotlib.pyplot as plt
import numpy as np
import sys
"ipympl" in sys.modules
True

# Testing matplotlib interactions with a simple plot
fig = plt.figure()
plt.plot(np.sin(np.linspace(0, 20, 100)));

Error displaying widget: model not found

Versions

Paste the command output here.

3.8.10 (default, Mar 13 2023, 10:26:41) 
[GCC 9.4.0]
ipympl version: 0.9.3
Selected Jupyter core packages...
IPython          : 8.12.0
ipykernel        : 6.13.0
ipywidgets       : 8.0.6
jupyter_client   : 8.2.0
jupyter_core     : 5.3.0
jupyter_server   : 2.5.0
jupyterlab       : 3.6.3
nbclient         : 0.7.4
nbconvert        : 7.3.1
nbformat         : 5.8.0
notebook         : 6.5.4
qtconsole        : not installed
traitlets        : 5.9.0
Known nbextensions:
  config dir: /usr/local/etc/jupyter/nbconfig
    notebook section
      jupyter-matplotlib/extension  enabled 
      - Validating: OK
      jupyter_resource_usage/main  enabled 
      - Validating: OK
      nbdime/index  enabled 
      - Validating: OK
      jupyter-js-widgets/extension  enabled 
      - Validating: OK
    tree section
      jupyter_server_proxy/tree  enabled 
      - Validating: OK
JupyterLab v3.6.3
/usr/local/share/jupyter/labextensions
        jupyterlab_pygments v0.2.2 enabled OK (python, jupyterlab_pygments)
        dask-labextension v6.1.0 enabled OK (python, dask_labextension)
        nbdime-jupyterlab v2.2.0 enabled OK
        jupyter-matplotlib v0.11.3 enabled OK
        jupyterlab-nvdashboard v0.8.0 enabled OK (python, jupyterlab_nvdashboard)
        @jupyterlab/git v0.41.0 enabled OK (python, jupyterlab-git)
        @jupyter-widgets/jupyterlab-manager v5.0.7 enabled OK (python, jupyterlab_widgets)
        @jupyterhub/jupyter-server-proxy v4.0.0 enabled OK
        @jupyter-server/resource-usage v0.7.2 enabled OK (python, jupyter-resource-usage)
        @jupyter-lsp/jupyterlab-lsp v4.1.0 enabled OK (python, jupyterlab-lsp)
        @elyra/code-snippet-extension v3.15.0 enabled OK
        @elyra/script-debugger-extension v3.15.0 enabled OK
        @elyra/python-editor-extension v3.15.0 enabled OK
        @elyra/metadata-extension v3.15.0 enabled OK
        @elyra/pipeline-editor-extension v3.15.0 enabled OK
        @elyra/code-viewer-extension v3.15.0 enabled OK
        @elyra/theme-extension v3.15.0 enabled OK
        @elyra/r-editor-extension v3.15.0 enabled OK
        @elyra/scala-editor-extension v3.15.0 enabled OK

Other labextensions (built into JupyterLab)
   app dir: /usr/local/share/jupyter/lab


Disabled extensions:
    @jupyterlab/launcher-extension (all plugins)

[aaronsheldon]

Whack-a-mole on this with "Model not found":

• VSCode 1.93.1
• Jupyter Renderer 1.0.19
• Conda
• win64
• Python 3.12.5
• ipympl 0.8.7
• Matplotlib 3.9.2
• JupyterLab 4.2.5

It has been years of this on-again off-again brittle behavior of ipympl in VSCode or JupyterLab. I don't see how after this long this can claim to be stably supported in VSCode or JupyterLab.