Fix issue with keyerror in list comprehension

Small fix for issue #773

[ ] I have built and tested the code locally and in a deployed app
[ ] For frontend changes, I have pulled the latest code from main, built the frontend, and committed all static files.
[ ] This is a change for all users of this app. No code or asset is specific to my use case or my organization.
[ ] I didn't break any existing functionality :smile:

microsoft / sample-app-aoai-chatGPT