Comment 34 for bug 2060534

I _think_ this might the same issue as Bug 1890135.
If so, the problem occurs when you compact folders which have had _all_ their messages deleted.
Can anyone confirm this?

If it's not the case, then I have actually re-written all message compaction code, and will be aiming to get that reviewed to land in the next week or so. It's much simpler and robust than the old compaction code, and much better at cleaning up after errors!