Errors were not (v)sprintf'ed in Error_Context if the error string didn't start with error_

Signed-off-by: emanuele <emanuele45@gmail.com>
email_in_use error should not be logged

Signed-off-by: emanuele <emanuele45@gmail.com>
And use the fatal error during registration only if actually necessary

Signed-off-by: emanuele <emanuele45@gmail.com>
If an (unexpected) error has been generated, better know, though let's not count it (yet) as an exception

Signed-off-by: emanuele <emanuele45@gmail.com>