Mercurial native migration: user feedback on errors
Currently, if there is an error, the process just stops, the project stays archived and the banner disappears after a few minutes (expiration of the exclusive lease in Redis). Errors can be seen in logs, but that requires systems administrator level acces.
This is obviously suboptimal, we need to provide users with proper feedback. Email is maybe an option to avoid the need to add persistence for errors (would require a new table).