Fix crash when running with directories that are not 6-digit DSIDs
Description of bug
Running of the dsid parsing relies on 6-digit DSIDs, so it should only be done after real DSIDs have been booked.
Running it outside the if (( $NbookedDSIDs > 0 ))
statement was causing the crash reported in #133 (closed)
Changes introduced
Only call the DSID parsing code when DSIDs are actually booked.
Tests
Issues resolved
Closes #133 (closed)