Account Applications; Attempting to create Client from Applicant on unsaved Application fails with "Invalid Applicant index." error

If you add a new Account Application and then, without saving it, go to the Applicants page and add a new Applicant and then try to add a Client from this Applicant via the button on the Applicant Properties form, an "Invalid Applicant Index." error may occur.

The form will first show a warning that the Application must be saved and Edit mode existed but upon clicking the "OK" button, instead of doing nothing, you would still be properted to create the Client record which would then fail.