[bug] Uncaught exception: MultiValueDictKeyError at /admin/config/device/add/

[nemesifier]

Describe the bug
An uncaught exception is raised if a user submits an empty add device form:

MultiValueDictKeyError at /admin/config/device/add/

Steps To Reproduce
Steps to reproduce the behavior:

1. Add a new device
2. Click on "+ Add another Configuration"
3. Hit save and continue

Expected behavior
A validation error should be shown in the UI, but the uncaugh exception is raised instead.

Screenshots

System Information:

• current dev version (1.2.0a)