Error displaying widget: model not found

[habibutsu]

$ pip list|grep ipycanvas
ipycanvas            0.10.2

$ jupyter labextension list
JupyterLab v3.2.1
/usr/local/share/jupyter/labextensions
        ipycanvas v0.10.2 enabled OK
        @jupyter-widgets/jupyterlab-manager v3.0.1 enabled OK (python, jupyterlab_widgets)

Other labextensions (built into JupyterLab)
   app dir: /usr/local/share/jupyter/lab
        jupyter-matplotlib v0.3.0 enabled OK