Interface Bulk edit fails if vlan_group is set to null

[jiuka]

NetBox version

v3.5.6

Python version

3.8

Steps to Reproduce

1. Select multiple Interfaces and click on Edit below the list.
2. Activate Set Null for the 802.1Q Switching> VLAN group option
3. Click on save

Expected Behavior

There is no Set Null option as the group is used for filtering only or at least no error is raised.

Observed Behavior

Server Error is raised.

<class 'AttributeError'>

'NoneType' object has no attribute 'null'

Python version: 3.8.10
NetBox version: 3.5.6