Yes, seems like a bug.  It looks like the intention is to handle the case where n=0.  This would result in curVector=-1.  Since it is unsigned this would break things so there should probably be a check before assigning curVector_ that instead sets curVector to be the last vector (using vectorFile.vectorCount() to determine it, although that looks to be off-by-one in this case as well).

Ultimately I am not sure how to test this or where it is used so it is a little tricky changing it for fear that we are misinterpreting it.  Will leave to your judgement.