Steps to reproduce:

1. Go to any LLD using SNMP (i.e Linux by SNMP template > Network interfaces discovery)
2. Go to the Preprocessing tab
3. Into the list of preprocessing step, try to click Add into the Parameters' column of a SNMP walk to JSON step

Result:
No action seen on the interface
Into the browser dev console, we can see an error about a funciton call

Expected:

Add new preprocessing parameters