Nbgrader Menu in JupyterLab opens windows that cannot be closed

[ykazakov]

Operating system

MacOS 13.2.1 (22D68)

nbgrader --version

% nbgrader --version     
Python version 3.11.1 | packaged by conda-forge | (main, Mar 30 2023, 16:46:19) [Clang 14.0.6 ]
nbgrader version 0.8.2

jupyter notebook --version

Not using jupyter notbook but jupyter lab:

% jupyter notebook --version
6.5.3
% jupyter lab --version
3.5.3

Expected behavior

The windows opened by Nbgrader menus (Assignment List, Formgrder, Course List) should be closable.

Actual behavior

If a window is opened the second time (e.g., Nbgrader > Formgrader, close, Nbgrader > Formgrader), the widow no longer has title and cannot be closed. See the screenshot:

Steps to reproduce the behavior

1. Install nbgrader and jupyter lab:

mamba create -n nbg -c conda-forge python -y
mamba activate nbg
mamba install jupyterlab  
pip install nbgrader # the latest version is not yet on conda-forge

2. Setup a course

mkdir -p /Users/Shared/nbgrader
cd /Users/Shared/nbgrader
nbgrader quickstart course101
% cat ~/.jupyter/nbgrader_config.py 
c = get_config()
c.Exchange.root = "/tmp/nbgrader/exchange"
c.CourseDirectory.root = "/Users/Shared/nbgrader/course101"

3. Start jupter lab

% jupyter lab

4. Open menu Nbgrader > Formgrader (or Assignment List or Course List)
5. Close the opened window Formgrader
6. Open the same window again: Nbgrader > Formgrader
   The result is shown in the screenshot above

Further details

Upon opening the menu second time (Step 6) the browser console (Safari) shows the following messages:

[Warning] A disposed object cannot be added. – je {_flags: 5, _layout: null, _parent: null, …} (jlab_core.6144df8e3fe03e33f880.js, line 2)
je {_flags: 5, _layout: null, _parent: null, _disposed: e, _hiddenMode: 0, …}je
[Error] Unhandled Promise Rejection: Error: A disposed object cannot be added.
	(anonymous function) (jlab_core.6144df8e3fe03e33f880.js:2:83513)
	asyncFunctionResume
	(anonymous function)
	promiseReactionJobWithoutPromise
	promiseReactionJob
[Error] TypeError: null is not an object (evaluating 'this.layout.widgets') — jlab_core.6144df8e3fe03e33f880.js:2:1605607
	m (jlab_core.6144df8e3fe03e33f880.js:2:1546745)
	b (jlab_core.6144df8e3fe03e33f880.js:2:1547162)
	t (jlab_core.6144df8e3fe03e33f880.js:2:1545706)
	y (jlab_core.6144df8e3fe03e33f880.js:2:1547390)

JupyterLab Log

I 2023-03-31 14:39:09.777 ServerApp] jupyterlab | extension was successfully linked.
[I 2023-03-31 14:39:09.779 ServerApp] nbclassic | extension was successfully linked.
[I 2023-03-31 14:39:09.779 ServerApp] nbgrader.server_extensions.assignment_list | extension was successfully linked.
[I 2023-03-31 14:39:09.779 ServerApp] nbgrader.server_extensions.course_list | extension was successfully linked.
[I 2023-03-31 14:39:09.779 ServerApp] nbgrader.server_extensions.formgrader | extension was successfully linked.
[I 2023-03-31 14:39:09.779 ServerApp] nbgrader.server_extensions.validate_assignment | extension was successfully linked.
[I 2023-03-31 14:39:09.928 ServerApp] notebook_shim | extension was successfully linked.
[I 2023-03-31 14:39:09.966 ServerApp] notebook_shim | extension was successfully loaded.
[I 2023-03-31 14:39:09.966 LabApp] JupyterLab extension loaded from /opt/homebrew/Caskroom/mambaforge/base/envs/nbg/lib/python3.11/site-packages/jupyterlab
[I 2023-03-31 14:39:09.966 LabApp] JupyterLab application directory is /opt/homebrew/Caskroom/mambaforge/base/envs/nbg/share/jupyter/lab
[I 2023-03-31 14:39:09.967 ServerApp] jupyterlab | extension was successfully loaded.

  _   _          _      _
 | | | |_ __  __| |__ _| |_ ___
 | |_| | '_ \/ _` / _` |  _/ -_)
  \___/| .__/\__,_\__,_|\__\___|
       |_|
                                                                           
Read the migration plan to Notebook 7 to learn about the new features and the actions to take if you are using extensions.

https://jupyter-notebook.readthedocs.io/en/latest/migrate_to_notebook7.html

Please note that updating to Notebook 7 might break some of your extensions.

[I 2023-03-31 14:39:09.969 ServerApp] nbclassic | extension was successfully loaded.
[I 2023-03-31 14:39:09.970 ServerApp] Loading the assignment_list nbgrader serverextension
[I 2023-03-31 14:39:09.970 ServerApp] nbgrader.server_extensions.assignment_list | extension was successfully loaded.
[I 2023-03-31 14:39:09.970 ServerApp] Loading the course_list nbgrader serverextension
[I 2023-03-31 14:39:09.970 ServerApp] nbgrader.server_extensions.course_list | extension was successfully loaded.
[I 2023-03-31 14:39:09.970 ServerApp] Loading the formgrader nbgrader serverextension
[I 2023-03-31 14:39:09.979 ServerApp] nbgrader.server_extensions.formgrader | extension was successfully loaded.
[I 2023-03-31 14:39:09.979 ServerApp] Loading the validate_assignment nbgrader serverextension
[I 2023-03-31 14:39:09.979 ServerApp] nbgrader.server_extensions.validate_assignment | extension was successfully loaded.
[I 2023-03-31 14:39:09.980 ServerApp] The port 8888 is already in use, trying another port.
[I 2023-03-31 14:39:09.980 ServerApp] Serving notebooks from local directory: /Users/Shared/nbgrader
[I 2023-03-31 14:39:09.980 ServerApp] Jupyter Server 1.23.4 is running at:
[I 2023-03-31 14:39:09.980 ServerApp] http://localhost:8889/lab?token=85a8ceab9bd094b4b872c6b0efc6c9655c16026124b5c70c
[I 2023-03-31 14:39:09.980 ServerApp]  or http://127.0.0.1:8889/lab?token=85a8ceab9bd094b4b872c6b0efc6c9655c16026124b5c70c
[I 2023-03-31 14:39:09.980 ServerApp] Use Control-C to stop this server and shut down all kernels (twice to skip confirmation).
[C 2023-03-31 14:39:09.983 ServerApp] 
    
    To access the server, open this file in a browser:
        file:///Users/ecull/Library/Jupyter/runtime/jpserver-76178-open.html
    Or copy and paste one of these URLs:
        http://localhost:8889/lab?token=85a8ceab9bd094b4b872c6b0efc6c9655c16026124b5c70c
     or http://127.0.0.1:8889/lab?token=85a8ceab9bd094b4b872c6b0efc6c9655c16026124b5c70c
This version of python seems to be incorrectly compiled
(internal generated filenames are not absolute).
This may make the debugger miss breakpoints.
Related bug: http://bugs.python.org/issue1666807
[E 2023-03-31 14:39:11.699 ServerApp] Uncaught exception GET /lab/api/settings?1680266351580 (::1)
    HTTPServerRequest(protocol='http', host='localhost:8889', method='GET', uri='/lab/api/settings?1680266351580', version='HTTP/1.1', remote_ip='::1')
    Traceback (most recent call last):
      File "/opt/homebrew/Caskroom/mambaforge/base/envs/nbg/lib/python3.11/site-packages/tornado/web.py", line 1713, in _execute
        result = await result
                 ^^^^^^^^^^^^
    tornado.iostream.StreamClosedError: Stream is closed
[W 2023-03-31 14:39:12.960 LabApp] Could not determine jupyterlab build status without nodejs
[I 2023-03-31 14:41:19.353 ServerApp] Released assignments:
[I 2023-03-31 14:41:19.359 ServerApp] Released assignments:
[I 2023-03-31 14:41:19.362 ServerApp] Released assignments:
[I 2023-03-31 14:41:19.433 ServerApp] Released assignments:
[I 2023-03-31 14:41:19.433 ServerApp] Released assignments:
[I 2023-03-31 14:41:19.433 ServerApp] Released assignments:
[I 2023-03-31 14:42:17.069 ServerApp] Released assignments:
[I 2023-03-31 14:42:17.073 ServerApp] Released assignments:
[I 2023-03-31 14:42:17.076 ServerApp] Released assignments:
[I 2023-03-31 14:42:17.094 ServerApp] Released assignments:
[I 2023-03-31 14:42:17.094 ServerApp] Released assignments:
[I 2023-03-31 14:42:17.095 ServerApp] Released assignments:

[ykazakov]

A related issue for the JupyterLab extension tutorial:
jupyterlab/jupyterlab_apod#3

The proposed solution is to recreate a widget if it is disposed:
jupyterlab/jupyterlab_apod#3 (comment)

[perllaghu]

I can confirm this is repeatable in Firefox, Chromium, and Edge browsers, on an Ubuntu system

(and note this is a duplicate of #1722 )