Posting Comment: `RuntimeError: Index out of bounds`

[fho]

When I add a comment to a line that was added in the PR, I get the following error when sending the PR after pressing <leader> c:

Posting comment to GitHub...                                                                                                                                                                                                                           
Comment posted successfully.
RuntimeError: Index out of bounds

The comment appears on github, but as PR comment, not line comment