[ticket/14403] Don't expect user_id and user_ip in phpbb\log

PHPBB3-14403

phpBB/phpbb/log/log.php

@@ -229,8 +229,8 @@ class log implements \phpbb\log\log_interface
 		}
 
 		$sql_ary = array(
-			'user_id'		=> $user_id,
-			'log_ip'		=> $log_ip,
+			'user_id'		=> !empty($user_id) ? $user_id : ANONYMOUS,
+			'log_ip'		=> !empty($log_ip) ? $log_ip : '',
 			'log_time'		=> $log_time,
 			'log_operation'	=> $log_operation,
 		);