This might be happening because lemmy returned no comments (could be a blocked user/community, or a deleted comment.

I would assume the dev would need to add some check prior to trying to insert comments that don’t exist, but not familiar with how it works in Eternity

It seems like it’s an issue with deleted comments. I’ve put together a fix in my latest commit, so that it will not crash at least. Could you verify this on the latest nightly?