Corrupt Notebook: NotJSONError when opening 3_keras_sequential_api.ipynb

Describe the bug In the Google Cloud course lab environment (Vertex AI Workbench), the notebook 3_keras_sequential_api.ipynb is corrupt and fails to open. JupyterLab displays a NotJSONError, indicating the file is not valid JSON.

Course/Lab Details This file is part of the training-data-analyst repository, in the following path: courses/machine_learning/deepdive2/introduction_to_tensorflow/labs/3_keras_sequential_api.ipynb

Steps to Reproduce

Start the Google Cloud lab associated with the "Introduction to TensorFlow" course.

Open the JupyterLab environment.

In the file browser, navigate to /home/jupyter/training-data-analyst/courses/machine_learning/deepdive2/introduction_to_tensorflow/labs/.

Double-click the file 3_keras_sequential_api.ipynb to open it.

See the "File Load Error" modal dialog.

Expected behavior The notebook should open normally.

Actual behavior An error dialog appears with the following message:

File Load Error for 3_keras_sequential_api.ipynb

Unreadable Notebook: /home/jupyter/training-data-analyst/courses/machine_learning/deepdive2/introduction_to_tensorflow/labs/3_keras_sequential_api.ipynb NotJSONError('Notebook does not appear to be JSON: \'{\\n "cells": [\\n {\\n "cell_type": "m...')

Troubleshooting Already Performed This error persists even after standard troubleshooting, which suggests the file in the repository may be corrupt:

Restarted the Jupyter Kernel and performed a hard refresh of the browser.

Deleted the entire training-data-analyst directory (rm -rf training-data-analyst).

Re-cloned the repository with git clone https://github.com/GoogleCloudPlatform/training-data-analyst.git.

Even with a fresh clone, the file still fails to load with the same NotJSONError. This suggests the version on the main branch may be broken.