Cannot use ipywidgets IntRangeSlider with panel

[alejandrosame]

ALL software version info

(this library, plus any other relevant software, e.g. bokeh, python, notebook, OS, browser, etc)

[GCC 7.5.0] :: Anaconda, Inc. on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import panel
>>> import bokeh
>>> import ipywidgets
>>> ipywidgets.__version__
'7.6.5'
>>> bokeh.__version__
'2.4.1'
>>> panel.__version__
'0.12.4'

Description of expected behavior and the observed behavior

I expect to send ipywidgets IntRangeSlider directly to panel and be able to interact with it. Currently, IntRangeSlider does not render and returns a NaN range, without showing any console error.

Complete, minimal, self-contained example code that reproduces the issue

#!/usr/bin/env python

import ipywidgets as widgets
import panel as pn

pn.extension(sizing_mode='stretch_width', comms='ipywidgets')

pn_slider = pn.widgets.IntRangeSlider(
    name='Integer Range Slider',
    start=0, end=10, value=(2, 8), step=2)

ipw_slider = widgets.IntRangeSlider(
    description='Integer Range Slider',
    min=0, max=10, value=[2, 8], step=2)

g = pn.Column(pn_slider, ipw_slider)


g.show()

Stack traceback and/or browser JavaScript console output

[bokeh] Lost websocket 0 connection, 1001 () bokeh.min.js:587:4014
http://localhost:39305/static/extensions/ipywidgets_bokeh/ ipywidgets_bokeh.js:2:208
[bokeh] setting log level to: 'info' bokeh.min.js:184:1360
GEThttp://localhost:39305/favicon.ico
[HTTP/1.1 404 Not Found 1ms]

[bokeh] Websocket connection 0 is now open bokeh.min.js:587:3565
Starting WebSocket: api/kernels/0 ipywidgets_bokeh.js:2:540510
Bokeh items were rendered successfully bokeh.min.js:163:888
[bokeh] document idle at 93 ms

Screenshots or screencasts of the bug in action

[philippjfr]

Updated your example but I can still confirm this errors on 0.12.5 with the following console error:

Uncaught TypeError: Cannot read properties of undefined (reading 'toggleClass')

Probably has to be raised with ipywidgets_bokeh rather than here.

[alejandrosame]

Thanks for the pointer @philippjfr!

At least one issue in ipywidgets_bokeh mentions this problem (bokeh/ipywidgets_bokeh#22), so I leave it linked here for reference.