Error loading server extension sagemaker_studio_autoshutdown

Hi, I just installed the auto-shutdown extension using LCC, but the extension fails to load. JupyterLab version is 3.0 and I am running the SageMaker Studio using vpconly mode.

The content of LCC script is shown below:
```
#!/bin/bash
# This script installs the idle notebook auto-checker server extension to SageMaker Studio
# The original extension has a lab extension part where users can set the idle timeout via a Jupyter Lab widget.
# In this version the script installs the server side of the extension only. The idle timeout
# can be set via a command-line script which will be also created by this create and places into the
# user's home folder
#
# Installing the server side extension does not require Internet connection (as all the dependencies are stored in the
# install tarball) and can be done via VPCOnly mode.

set -eux

# timeout in minutes
export TIMEOUT_IN_MINS=120

# Should already be running in user home directory, but just to check:
cd /home/sagemaker-user

# By working in a directory starting with ".", we won't clutter up users' Jupyter file tree views
mkdir -p .auto-shutdown

# Create the command-line script for setting the idle timeout
cat > .auto-shutdown/set-time-interval.sh << EOF
#!/opt/conda/bin/python
import json
import requests
TIMEOUT=${TIMEOUT_IN_MINS}
session = requests.Session()
# Getting the xsrf token first from Jupyter Server
response = session.get("http://localhost:8888/jupyter/default/tree")
# calls the idle_checker extension's interface to set the timeout value
response = session.post("http://localhost:8888/jupyter/default/sagemaker-studio-autoshutdown/idle_checker",
json={"idle_time": TIMEOUT, "keep_terminals": False},
params={"_xsrf": response.headers['Set-Cookie'].split(";")[0].split("=")[1]})
if response.status_code == 200:
print("Succeeded, idle timeout set to {} minutes".format(TIMEOUT))
else:
print("Error!")
print(response.status_code)
EOF
chmod +x .auto-shutdown/set-time-interval.sh

# This is the bucket I created to upload tar, and I confirmed that it's downloaded under .auto-shutdown
aws s3 cp s3://test-bucket-20220912/sagemaker_studio_autoshutdown-0.1.5.tar.gz .auto-shutdown/extension.tar.gz

# Installs the extension
cd .auto-shutdown
tar xzf extension.tar.gz
cd sagemaker_studio_autoshutdown-0.1.5

# Activate studio environment just for installing extension
export AWS_SAGEMAKER_JUPYTERSERVER_IMAGE="${AWS_SAGEMAKER_JUPYTERSERVER_IMAGE:-'jupyter-server'}"
if [ "$AWS_SAGEMAKER_JUPYTERSERVER_IMAGE" = "jupyter-server-3" ] ; then
eval "$(conda shell.bash hook)"
conda activate studio
fi;
pip install --no-dependencies --no-build-isolation -e .
jupyter serverextension enable --py sagemaker_studio_autoshutdown
if [ "$AWS_SAGEMAKER_JUPYTERSERVER_IMAGE" = "jupyter-server-3" ] ; then
conda deactivate
fi;

# Restarts the jupyter server
nohup supervisorctl -c /etc/supervisor/conf.d/supervisord.conf restart jupyterlabserver

# Waiting for 30 seconds to make sure the Jupyter Server is up and running
sleep 30

# Calling the script to set the idle-timeout and active the extension
/home/sagemaker-user/.auto-shutdown/set-time-interval.sh```

Start by reviewing the LCC script, the extracted sagemaker_studio_autoshutdown-0.1.5 package, and the jupyter serverextension enable command. Reproduce the installation on JupyterLab 3.0 in SageMaker Studio VPCOnly mode and inspect the reported loading error. Done means the server extension loads successfully and the supplied set-time-interval.sh script works.

Written by the indexing model from the issue text.