Synology DiskStation SNMPv3: returned disk bad sector value is -1, template data type is unsigned

[szpeter80]

I have a DS920+ with latest DSM released.
I'm using Zabbix 7.0.1 with the latest version of the template "Synology DiskStation SNMPv3" from 6.4

There is a discovery rule "Synology Disk(s)" which discovers physical disks plugged to the chassis.
It has an item prototype '{#SNMPVALUE} Bad sectors count'

The data type for this is unsigned integer, but my box returns "-1" as a value, so the intem is in error state with the message:

Value of type "string" is not suitable for value type "Numeric (unsigned)". Value "-1"

Two solutions come to my mind:

1. Add a preprocessing step to turn everything below zero to zero
2. change the data type to signed integer

What would be the correct resolution ?