'NoneType' object has no attribute 'lookup'

[ddrinka]

Library	Version
VS Code	1.71.2
python	3.9.13 64-bit
panel	0.13.1 0.14.0a25
jupyterlab	3.4.6
bokeh	2.4.3
jupyter-bokeh	3.0.5
pandas	1.4.4
ipywidgets	8.0.2

I'm using the Panel Getting Started notebook in Visual Studio Code. After hardcoding the comms implementation (holoviz/panel#3876) the matplotlib functionality works great. While the Bokeh functionality initially works, after the first batch of slider adjustments, a load of exceptions are thrown:

I saw #167 experiencing this issue as well, which doesn't actually appear to be related to the "single document" stuff @axil is running into.