Changing the supporter type does not warn if the active dropdown target field does not exist in the new support type

Steps to reproduce:
Use the "Drop-down Lookup" auto-target type and the "Email Full" supporter type.
Set the dropdown lookup to use the country field and save.
Change the supporter type to "Email Standard Canada" which does not have a country field (or any drop down fields) and save.
Go back to the email settings and notice that the down field is greyed out with no options. However the settings for the previously selected country field still display.
This also results in a PHP Notice:

Notice: Undefined index: #language in cce_select_field_lookup_supporter_form_alter() (line 157 of /home/lola/workspace/CITCON/profiles/citcon_starter/modules/contrib/citcon/modules/citcon_email/plugins/target/cce_select_field_lookup/cce_select_field_lookup.inc).

The system should not allow changing the supporter type if the dropdown field are in use in the auto-target selection.
If tokens for those fields are in use this may just be a warning.
Possibly it could detect if the same fields do exist in the new supporter type and allow the change.