Constant error messages from net-snmp (snmpd) daemon

[bp81]

We are constantly getting this error in the system log when snmpd is enabled:

netsnmp_assert saved_requests[i] == request failed helpers/row_merge.c:295 netsnmp_row_merge_helper_handler()

This occurs on Netgate models 6100, 5100, 3100, and 2100. The snmp service otherwise seems to work fine, we have a monitoring tool that queries it and that works as you would expect. However, this error gets logged after every single snmp request made.

Given that everything is working it's not really urgent, but it would be useful to not spam our system log with these if it could be avoided. Does anyone know of a fix or what the cause is?