Add a login error intead of redirecting to resend_verify_account page when using verify account feature

[Nicolas Besnard]

Hi,

Looking at the `verify_account` account, it seems that there's no way to add an error on the login field when trying to create an account with an already existing email.

I'd prefer my user to see a message on the create account form rather being redirected to a new page.

Would you accept a PR to add this feature?

[Jeremy Evans]

What's the use case?  If a user creates an account, doesn't verify it, and the next day tries to create an account with the same email, I can't think of a reason why they would prefer to see an error message instead of a form to request the verification email get resent.

Thanks,

Jeremy