Return An Error From Custom Database Login Script That Does Not Emit `fp` nor `fu`

Problem statement

The documentation for Return an Error under Login Script Templates shows that you can only return errors that will emit either a fp or fu event. Is there a way to return an error not related to an invalid username or password?

Solution

It is only possible to return an fp or fu error, as the documentation referenced explains. The errors returned are for Failed Login (Incorrect Password) or Failed Login (Invalid Email/Username).