Unclear error message with require_snapshot and missing /etc/urbackup/snapshot.cfg

When a backupdir is configured with require_snapshot and the snapshot.cfg file is missing (as it is on a fresh installation), the error message itself seems to erroneously formatted. There is no hint as to what caused the error.

|Info|03/04/20 10:06|Starting unscheduled full file backup...
|Info|03/04/20 10:06|Backing up "root" without snapshot.
|Errors|03/04/20 10:06|Indexing files failed, because of error
|Errors|03/04/20 10:06|Constructing of filelist of "myhost" failed: error - index error
|Errors|03/04/20 10:06|Backup had an early error. Deleting partial backup.