src/Api.php
private function authenticationError()
    {
        if (empty($this->email) || empty($this->auth_key)) {
            return new WP_Error('authentication-error', 'Authentication information must be provided');
        }

        if (! is_email($this->email)) {
            return new WP_Error('authentication-error', 'Email is not valid');
        }

        return null;
    }
private function authenticationError()
    {
        if (empty($this->email) || empty($this->auth_key)) {
            return new WP_Error('authentication-error', 'Authentication information must be provided');
        }

        if (! is_email($this->email)) {
            return new WP_Error('authentication-error', 'Email is not valid');
        }

        return null;
    }
private function authenticationError ( ) { if ( empty ( $ this -> email ) || empty ( $ this -> auth_key ) ) { return new WP_Error ( 'authentication-error' , 'Authentication information must be provided' ) ; } if ( ! is_email ( $ this -> email ) ) { return new WP_Error ( 'authentication-error' , 'Email is not valid' ) ; } return null ; }
Return WP Error if this object does not contain necessary info to perform API requests.

@return null|WP_Error
Return WP Error if this object does not contain necessary info to perform API requests .