<?php

use mystic\forum\orm\Topic;

$formId = "addpost";
$topicId = $_GET["topic"] ?? throw new Exception("Missing topic id");
$topic = new Topic();
$topic->id = $topicId;
if (!$db->fetch($topic)) {
    http_response_code(404);
    msg_error("No topic exists with this id");
    exit;
}