Restore should fail if errors are reported in the snapshot

[brmzkw]

Tested with plakar v1.0.6

When running plakar backup /etc as an unprivileged user, some “permission denied” errors are expected, since a non-root user cannot read all files under /etc.

However, restoring the resulting snapshot completes successfully without any warnings or errors, and the restore command exits with status 0, even though some files were not backed up and therefore cannot be restored.

Should the restore command return a non-zero exit status, or at least emit warnings or errors, when the snapshot is incomplete and some files cannot be restored?