Issue Summary

No error on the Email Request configuration when field beside Summary and Description is set to required for request types

Steps to Reproduce

1. (Optionally) remove all the request type to isolate this case and create a new Request Type.
2. On the request type, include the Summary and Description field to have Email Request to work
3. Add another field and Set the field to required
4. Go to Email Request and click "Turn on email support"

Expected Results

Error message explaining how to set up a suitable Request Type should be displayed

Actual Results

Clicking on the button does nothing

The below exception is thrown in the xxxxxxx.log file:
From the Browser's network request console:

{
    "errors": [
        {
            "errorMessage": "To receive requests by email, you must have a request type with visible Summary and Description fields. All other request type fields must be optional. You can create a new request type or modify an existing one <a href=\"/servicedesk/admin/CLIENT/request-types\">here</a>."
        }
    ],
    "reasonKey": "sd.email.ondemand.mailbox.creation.failure.no.valid.request.type",
    "reasonCode": "400"
}

Workaround

Have at least one Request Type to include Summary and Description, field and other field should be set as optional in order to have the email request to work