Merged requested to merge grote/repomaker:115-locked-db into master
Unfortunately, I didn't find a way to improve the database locking when using SqLite. It is either locking all or nothing. Also, I couldn't find out how to lock the database only for short intervals while doing background tasks.
So this MR at least adds an error page, so users know what is going on.
Closes #115 (closed)