Getting “toml.decoder.TomlDecodeError: Key name found without value

[so_user]

While I got this error from logs:

I visited toml.decoder.py file I found the location of line where this error was raised:

With this error persiting I am getting following display when my app is deployed:
How can I solve this issue. I was trying to deploy a streamlit web app on heroku.

Thanks in advance.