このエラーメッセージに関する原因と対処に関して説明します。
エラーメッセージ(英語)：
jupyterlab widget not detected
対処
関連リンク
"Widget Javascript not detected" in jupyterlab v0.25.2 ・ Issue ...github.com/jupyter-widgets/ipywidgets/issues/1527
https://github.com/jupyter-widgets/ipywidgets/issues/1527
Widget Javascript not detected in jupyterlab ・ Issue #2036 ...github.com/jupyter-widgets/ipywidgets/issues/2036
https://github.com/jupyter-widgets/ipywidgets/issues/2036
JavaScript "jupyterlab widget not detected"のヤフオク!検索結果（341件）ヤフオク!
https://auctions.yahoo.co.jp/search/search?rkf=2&p=JavaScript+%22jupyterlab+widget+not+detected%22&a・・・