Config revision view error when using custom validators

[jonatangobbato]

NetBox version

v3.6.1

Python version

3.8

Steps to Reproduce

1. Create Custom Validator
   EX:

from extras.validators import CustomValidator

class cvReservationMAC(CustomValidator):
    def validate(self, instance):
        if instance.status == 'dhcp' and not instance.cf["MAC_Address"]:
            self.fail("DHCP Reservations must have Mac Address!", field='cf_MAC_Address')

class cvReservationDNSName(CustomValidator):
    def validate(self, instance):
        if instance.status == 'dhcp' and not instance.dns_name:
            self.fail("DHCP Reservations must have DNS Name!", field='dns_name')

CUSTOM_VALIDATORS = {
    'ipam.ipaddress': (
        cvReservationMAC(),
        cvReservationDNSName(),
    )
}

3. Open menu "Admin >> Current Config" Click on Edit

Expected Behavior

Edit config context appears

Observed Behavior