radia_viewer broken on jupyter

[cchall]

This might really be an issue more with our jupyter environment (this is not the only widget error currently causing problems) but I'll put it here to start.
Using the radia_viewer on our jupyterhub gives an error:

Error displaying widget: model not found

For an example try: https://github.com/radiasoft/Radia-Examples/blob/master/Radia_Ex01.ipynb

[e-carlin]

Thanks @cchall. I'll take a look.

[e-carlin]

radiasoft/container-beamsim-jupyter-base#113 may have helped fix this. But, I'm still seeing "Error displaying widget: model not found". In the browser console I see "TypeError: Class constructor ws cannot be invoked without 'new'" which I wasn't seeing when debugging other widget issues. Could be a red herring.