Howt to redirect to a custom error page in SignIn callback

[B4tzz]

I'm introducing new rules in an existing website that blocks login of users that doesn't have the proper permission. I can successful get who has access or no, but I'm can't make works a redirect to a custom page to display the error message. How can I make this redirect? If returns false NextAuth redirects to a default error page, I need to redirect to a custom page.

note: if the user trying to login don't have access, the API returns 404 code, so the catch block is executed.