Kernel fails to start, resulting in timeout

[joh]

Describe the bug
On jupyter notebook 7.0.4, the kernel fails to start and jupynium times out. The issue seems to be related to the way jupyter command is started from jupinium using subprocess.Popen where only stdout is attached and not stderr.

To Reproduce
Steps to reproduce the behavior:

Open any .ju.py file, then run JupyniumStartAndAttachToServer followed by JupyniumStartSync.

Expected behavior
The JupyniumStartSync command hangs until timing out after 30s.

Logs in /tmp/jupynium/logs/
The tmp directory path can be different in a different OS.
Alternatively, run :JupyniumStartAndAttachToServerInTerminal to see the output directly in neovim.

2023-10-02 11:49:17,124 - jupynium.pynvim_helpers: 11 - INFO - nvim addr: /run/user/1000/nvim.1144391.0
2023-10-02 11:49:17,128 - jupynium.pynvim_helpers: 30 - INFO - nvim attached
2023-10-02 11:49:17,128 - jupynium.pynvim_helpers: 34 - INFO - Initialising..
2023-10-02 11:49:17,128 - jupynium.pynvim_helpers: 35 - INFO - Communicating with channel_id 11
2023-10-02 11:49:17,133 - jupynium.cmds.jupynium: 93 - INFO - Using firefox profile: None
2023-10-02 11:49:18,473 - jupynium.cmds.jupynium: 397 - INFO - Writing Jupyter Notebook server log to: /tmp/tmp
sjqwjfgy
2023-10-02 11:49:22,847 - jupynium.events_control: 197 - INFO - Event from nvim: ['request', 'start_sync', [1,
'', True, ['# %%', 'print("hello, world")', 'plt.plot([1, 2, 1])', '', '# %%', 'import plotly.express as px', 'p
x.scatter(y=[1, 2, 1])', '', '# %% [markdown]', '"""', 'Hello, this is my markdown', '"""', '', '# %%', "var =
'foo'"], 'python', None], <pynvim.msgpack_rpc.async_session.Response object at 0x7f282babced0>]
2023-10-02 11:49:53,929 - jupynium.selenium_helpers: 38 - ERROR - Timed out waiting for kernel to load
Traceback (most recent call last):
File "/home/joh/code/jupynium.nvim/src/jupynium/selenium_helpers.py", line 32, in wait_until_notebook_loaded
WebDriverWait(driver, timeout).until(
File "/home/joh/.local/lib/python3.11/site-packages/selenium/webdriver/support/wait.py", line 95, in until
raise TimeoutException(message, screen, stacktrace)
selenium.common.exceptions.TimeoutException: Message:

2023-10-02 11:49:54,415 - urllib3.connectionpool: 824 - WARNING - Retrying (Retry(total=2, connect=None, read=None, redirect=None, status=None)) after connection broken by 'NewConnectionError('<urllib3.connection.HTTPConnection object at 0x7f282bac0490>: Failed to establish a new connection: [Errno 111] Connection refused')': /session/eb7514c4-c2ce-466c-a34c-8d749b2ee1c3/window

Output of jupynium --version

Jupynium v0.2.1

Output of nvim --version

NVIM v0.9.1