Server error? tornado.websocket.WebSocketClosedError

Hi! When I launch the lab with jupyter lab in my base conda environment (miniconda-3-latest, since I have installed it via pyenv), the server is started. However, after that I this error message keeps being printed:

[E 2021-10-12 22:22:24.879 ServerApp] Exception in callback <bound method WebSocketMixin.send_ping of ZMQChannelsHandler(7df4a061-9d5c-475e-a62e-939900d1e04f)>
    Traceback (most recent call last):
      File "/Users/luca/.pyenv/versions/miniconda3-latest/lib/python3.9/site-packages/tornado/ioloop.py", line 905, in _run
        return self.callback()
      File "/Users/luca/.pyenv/versions/miniconda3-latest/lib/python3.9/site-packages/jupyter_server/base/zmqhandlers.py", line 189, in send_ping
        self.ping(b"")
      File "/Users/luca/.pyenv/versions/miniconda3-latest/lib/python3.9/site-packages/tornado/websocket.py", line 445, in ping
        raise WebSocketClosedError()
    tornado.websocket.WebSocketClosedError

I could not find any other situation like this here on Discourse, nor GitHub. Here are the extensions I use:

JupyterLab v3.1.18
/Users/luca/.pyenv/versions/miniconda3-latest/share/jupyter/labextensions
        jupyterlab-jupytext v1.3.1 enabled OK (python, jupytext)
        nbdime-jupyterlab v2.1.0 enabled OK
        jupyterlab-citation-manager v0.1.3 enabled OK (python, jupyterlab-citation-manager)
        @ijmbarr/jupyterlab_spellchecker v0.7.2 enabled OK (python, jupyterlab-spellchecker)
        @mamba-org/gator-lab v3.0.2 enabled OK (python, mamba_gator)
        @krassowski/jupyterlab-lsp v3.8.1 enabled OK (python, jupyterlab-lsp)
        @ryantam626/jupyterlab_code_formatter v1.4.10 enabled OK (python, jupyterlab-code-formatter)
        @jupyterlab/git v0.33.0 enabled OK (python, jupyterlab-git)
        @jupyter-widgets/jupyterlab-manager v3.0.1 enabled OK (python, jupyterlab_widgets)
        @telamonian/theme-darcula v3.1.1 enabled OK (python, theme-darcula)

Other labextensions (built into JupyterLab)
   app dir: /Users/luca/.pyenv/versions/miniconda3-latest/share/jupyter/lab
        @aquirdturtle/collapsible_headings v3.0.0 enabled OK
        @jupyterlab/geojson-extension v3.1.2 enabled OK
        @jupyterlab/katex-extension v3.2.2 enabled OK
        jupyterlab-plotly v5.2.2 enabled OK


Disabled extensions:
    @jupyterlab/mathjax2-extension:plugin

The following source extensions are overshadowed by older prebuilt extensions:
    jupyterlab-jupytext

Thank you!