No extensions being shown

[graipher]

After installing the extensions, I do get the link to the extension configurator, but the page is all empty, except for the header:

The javascript console shows the following error(s):

main.js?v=20230921094128:1100 Uncaught TypeError: Cannot read properties of undefined (reading 'autocomplete')
    at filter_build_ui (main.js?v=20230921094128:1100:47)
    at build_configurator_ui (main.js?v=20230921094128:1263:9)
    at main.js?v=20230921094128:1336:9
    at Object.execCb (require.js?v=bd1aa102bdb0b27fbf712b32cfcd29b016c272acf3d864ee8469376eaddd032cadcf827ff17c05a8c8e20061418fe58cf79947049f5c0dff3b4f73fcc8cad8ec:1696:33)
    at Module.check (require.js?v=bd1aa102bdb0b27fbf712b32cfcd29b016c272acf3d864ee8469376eaddd032cadcf827ff17c05a8c8e20061418fe58cf79947049f5c0dff3b4f73fcc8cad8ec:883:51)
    at Module.enable (require.js?v=bd1aa102bdb0b27fbf712b32cfcd29b016c272acf3d864ee8469376eaddd032cadcf827ff17c05a8c8e20061418fe58cf79947049f5c0dff3b4f73fcc8cad8ec:1176:22)
    at Module.init (require.js?v=bd1aa102bdb0b27fbf712b32cfcd29b016c272acf3d864ee8469376eaddd032cadcf827ff17c05a8c8e20061418fe58cf79947049f5c0dff3b4f73fcc8cad8ec:788:26)
    at require.js?v=bd1aa102bdb0b27fbf712b32cfcd29b016c272acf3d864ee8469376eaddd032cadcf827ff17c05a8c8e20061418fe58cf79947049f5c0dff3b4f73fcc8cad8ec:1460:36
filter_build_ui @ main.js?v=20230921094128:1100
build_configurator_ui @ main.js?v=20230921094128:1263
(anonymous) @ main.js?v=20230921094128:1336
execCb @ require.js?v=bd1aa102bdb0b27fbf712b32cfcd29b016c272acf3d864ee8469376eaddd032cadcf827ff17c05a8c8e20061418fe58cf79947049f5c0dff3b4f73fcc8cad8ec:1696
check @ require.js?v=bd1aa102bdb0b27fbf712b32cfcd29b016c272acf3d864ee8469376eaddd032cadcf827ff17c05a8c8e20061418fe58cf79947049f5c0dff3b4f73fcc8cad8ec:883
enable @ require.js?v=bd1aa102bdb0b27fbf712b32cfcd29b016c272acf3d864ee8469376eaddd032cadcf827ff17c05a8c8e20061418fe58cf79947049f5c0dff3b4f73fcc8cad8ec:1176
init @ require.js?v=bd1aa102bdb0b27fbf712b32cfcd29b016c272acf3d864ee8469376eaddd032cadcf827ff17c05a8c8e20061418fe58cf79947049f5c0dff3b4f73fcc8cad8ec:788
(anonymous) @ require.js?v=bd1aa102bdb0b27fbf712b32cfcd29b016c272acf3d864ee8469376eaddd032cadcf827ff17c05a8c8e20061418fe58cf79947049f5c0dff3b4f73fcc8cad8ec:1460
2nbextensions:1 Uncaught (in promise) Error: The message port closed before a response was received.

The linked code in the last line of the error is lines 1460-1462 of require.js:

requireMod.init(deps, callback, errback, {
    enabled: true
});

Installing and enabling extensions manually via e.g. jupyter nbextension enable toc2/main works just fine.

Ubuntu 23.04
Python 3.11.4
IPython 8.5.0
Jupyter Notebook 6.4.12 (as system package via apt)
jupyter_nbextensions_configurator 0.6.3 (global via pip)