Bugfix: Correct restore progress information if an error occurs

If an error occurred while restoring a snapshot, this could cause the restore
progress bar to show incorrect information. In addition, if a data file could
not be loaded completely, then errors would also be reported for some already
restored files.

We have improved the error reporting of the restore command to be more accurate.

https://github.com/restic/restic/pull/4624
https://forum.restic.net/t/errors-restoring-with-restic-on-windows-server-s3/6943