ipywidget append causes client to disconnect

[apowers313]

This may be related to #14716

The following code (which was basically copied from the ipywidgets docs) causes VS Code to hang:

import ipywidgets as widgets
out = widgets.Output(layout={'border': '1px solid red'})

out.append_stdout('Output appended with append_stdout')
out.append_stdout('Output appended with append_stdout')

out

The notebook server shows the following error:

[12:15:04] [<unknown>][d9319778][ManagementConnection] The client has disconnected, will wait for reconnection 3h before disposing...

The only way to recover is to restart the kernel.

Other hints that may help identify a root cause:

• I can duplicate the error using other forms of ipywidgets append (e.g. append_display_data with a YouTubeVideo, as shown in the ipywidgets docs)
• A single append_stdout statement works fine
• If I have a cell with a single append_stdout, and then add a second cell with a second append_stdout then you can see the output appear before the client loses its connection.

My setup is:

code-server: v4.93.1
Code: 1.93.1
Commit: 3542bd157b0ccc8bf732acdb03d4d69d85f48ea9
Date: 2024-09-19T10:15:30.023Z (3 mos ago)
Browser: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/18.2 Safari/605.1.15