After reviewing the pull request code diff and description, here are some potential issues or downsides that I've identified:

1. Missing import: The add_issues_to_chroma function now requires a repo_id parameter, but there's no indication of how this parameter will be handled in other parts of the codebase.
2. No handling for NoneType error on creation: Although the title suggests fixing a bug related to NoneType errors, I couldn't find any changes that address this issue specifically. It's possible that the fix is more subtle and not directly visible in the code diff.
3. Changes in comment text: The new pull request has different comment texts for similar issues with high or low similarity thresholds. This might break existing logic or functionality if other parts of the system rely on these specific comments.
4. New behavior when no similar issues are found: The updated handle_new_issue function now leaves a comment indicating that "No similar issues were found." However, it's unclear whether this change is intended to be backwards compatible with previous behavior.

To consider these points, I'd like to ask the PR author:

Have you considered how these changes might affect existing functionality or logic in the codebase? Are there any potential side effects or interactions that need to be addressed before merging this pull request?