fixed a error on login without totp_code

application/libraries/Aauth.php

@@ -241,11 +241,11 @@ class Aauth {
 			$query = $this->aauth_db->where($db_identifier, $identifier);
 			$query = $this->aauth_db->where('totp_secret !=', '');
 			$query = $this->aauth_db->get($this->config_vars['users']);
-			$totp_secret =  $query->row()->totp_secret;
 			if ($query->num_rows() > 0 AND !$totp_code) {
 				$this->error($this->CI->lang->line('aauth_error_totp_code_required'));
 				return FALSE;
 			}else if ($query->num_rows() > 0 AND $totp_code) {
+				$totp_secret =  $query->row()->totp_secret;
 				$ga = new PHPGangsta_GoogleAuthenticator();
 				$checkResult = $ga->verifyCode($totp_secret, $totp_code, 0);
 				if (!$checkResult) {