I followed the following LLMWare tutorial on YouTube and ran into the following error when using `Prompter.add_source_document()`. `source = prompter.add_source_document(contracts_path, contract, query=key)` This gives me a Warning that the source was not added. What could be the issue? My `contracts_path = ./docs/`. My files do have spaces in their names, but I doubt that would be an issue. Could it be the file-type suffix? Tutorial Video Followed: https://www.youtube.com/watch?v=8aV5p3tErP0