The commit aca8e78 that was meant to fix parts of #17 seems to revert parts of the previous fix for extraction, causing it to fail. With the latest learnr devel, learnrhash::extract_hash fails due to a missing "id" column.
In addition, from what I can tell, the "exercise_submission" type used for extract_exercises was the old name (and similar for questions); the previous commit for fixing extractions changed it to "exercise" and "question", which was fine up until this latest "fix".
So it looks to me that the latest fix regressed to some old learnr format, rather than updating it to the latest.

I'm now trying to force my quizzes to load the previous learnrhash version, and that still works with the latest learnr devel version.