When adding an application, "Select..." can be added as a group

To replicate:
1) Add an application
2) On the `Authorisation` screen, select `Select...` in the `Directory groups` dropdown and click `Add Group`
3) The "group" gets added which is wrong because it's not a group
4) Add a second, real group
5) Finish creating the application
6) On the `Groups` tab of the application configuration you can see the "Select..." group present, so it was actually added

Expected behaviour:
Cannot add "Select..." as a group to new or existing applications