Duplicate.pm: "Use of uninitialized value in hash element" flooding logs

System:

# uname -a
Linux rz2hh298.rz2hh.ibb.lan 2.6.32-504.8.1.el6.x86_64 #1 SMP Fri Dec 19 12:09:25 EST 2014 x86_64 x86_64 x86_64 GNU/Linux

# cat /etc/redhat-release
Red Hat Enterprise Linux Server release 6.6 (Santiago)

OCS-Server Ver. 2.1.2

AGENT => Running OCS Inventory NG Agent Version 2.1.1.1
AGENT => Using OCS Inventory NG FrameWork Version 2.1.1.1

(Agent downloaded from the site: OCS Inventory NG Agents 2.1.2)

Error:

These entrys log in bursts of hundreds at once into "/var/log/httpd/error_log":

Use of uninitialized value in hash element at /usr/local/share/perl5/Apache/Ocsinventory/Server/Duplicate.pm line 147.

Around line 147 in Duplicate.pm:

    142   # Do we already have the assettag ?
    143   $request = $dbh->prepare('SELECT HARDWARE_ID, ASSETTAG FROM bios WHERE ASSETTAG=? AND HARDWARE_ID<>? ORDER BY HARDWARE_ID');
    144   $request->execute($result->{CONTENT}->{BIOS}->{ASSETTAG}, $DeviceID);
    145   while($row = $request->fetchrow_hashref()){
    146     if(!($row->{'ASSETTAG'} eq '')){
    147       $exist->{$row->{'ID'}}->{'ASSETTAG'}=1;
    148     }

How could the element be initialized? The Server is, besides that, running very well. Only the logs grow to gigabytes.

Greetings, Mbrock