DataLake file system and path are required when using Azure Data Lake Gen2

[thomasjsweet]

The instruction here:
https://github.com/Azure-Samples/azure-search-openai-demo/blob/main/docs/login_and_acl.md#azure-data-lake-storage-gen2-setup
state that file system and path are optional for the data lack storage.

#'To run this script with a Data Lake Storage Gen2 account, first set the following environment variables:

AZURE_ADLS_GEN2_STORAGE_ACCOUNT: Name of existing Data Lake Storage Gen2 storage account.
(Optional) AZURE_ADLS_GEN2_FILESYSTEM: Name of existing Data Lake Storage Gen2 filesystem / container in the storage account. If empty, gptkbcontainer is used.
(Optional) AZURE_ADLS_GEN2_FILESYSTEM_PATH: Specific path in the Data Lake Storage Gen2 filesystem / container to process. Only PDFs contained in this path will be processed.
Once the environment variables are set, run the scri'

I set AZURE_ADLS_GEN2_FILESYSTEM_PATH but did not set the other two as they were supposed to be optional.
My result is Traceback (most recent call last):
File "/workspaces/Azure-Search-AI-Demo/./app/backend/prepdocs.py", line 354, in
list_file_strategy = setup_list_file_strategy(
^^^^^^^^^^^^^^^^^^^^^^^^^
File "/workspaces/Azure-Search-AI-Demo/./app/backend/prepdocs.py", line 94, in setup_list_file_strategy
raise ValueError("DataLake file system and path are required when using Azure Data Lake Gen2")
ValueError: DataLake file system and path are required when using Azure Data Lake Gen2

expected result is that the two additional environment variables are optional.