I cannot reach the title of my forum

I'm trying to create a forum and I have it(more or less) but I cannot reach the title and other elements in the view of the single entrance.
This is the error message that I recieve:

PHP Code:

Severity: Warning

Message: Attempt to read property "title" on null

Filename: forum/single.php

Line Number: 7

Backtrace:

File: C:\xampp\htdocs\logopedas\application\views\forum\single.php
Line: 7
Function: _error_handler

File: C:\xampp\htdocs\logopedas\application\controllers\Forum.php
Line: 120
Function: view

File: C:\xampp\htdocs\logopedas\index.php
Line: 335
Function: require_once 


Here you can see the controller:

PHP Code:

public function index($slug = false) {
 
 // create the data object
 $data = new stdClass();
 
 if ($slug === false) {
 
 // create objects
 $forums = $this->forum_model->get_forums();
 
 foreach ($forums as $forum) {
 
 $forum->permalink    = base_url($forum->slug);
 $forum->topics      = $this->forum_model->get_forum_topics($forum->id);
 $forum->count_topics = count($forum->topics);
 $forum->count_posts  = $this->forum_model->count_forum_posts($forum->id);
 
 if ($forum->count_topics > 0) {
 
 // $forum has topics
 $forum->latest_topic            = $this->forum_model->get_forum_latest_topic($forum->id);
 $forum->latest_topic->permalink = $forum->slug . '/' . $forum->latest_topic->slug;
 $forum->latest_topic->author    = $this->user_model->get_username_from_user_id($forum->latest_topic->user_id);
 
 } else {
 
 // $forum doesn't have topics yet
 $forum->latest_topic = new stdClass();
 $forum->latest_topic->permalink = null;
 $forum->latest_topic->title = null;
 $forum->latest_topic->author = null;
 $forum->latest_topic->created_at = null;
 
 }
 
 }
 
 // create breadcrumb
 // $breadcrumb  = '<ol class="breadcrumb">';
 // $breadcrumb .= '<li class="active">Home</li>';
 // $breadcrumb .= '</ol>';
 
 // assign created objects to the data object
 $data->forums    = $forums;
 // $data->breadcrumb = $breadcrumb;
 
 // load views and send data
 $this->load->view('templates/header');
 $this->load->view('forum/index', $data);
 $this->load->view('templates/footer');
 
 } else {
 
 // get id from slug
 $forum_id = $this->forum_model->get_forum_id_from_forum_slug($slug);
 
 // create objects
 $forum    = $this->forum_model->get_forum($forum_id);
 $topics  = $this->forum_model->get_forum_topics($forum_id);
 
 // create breadcrumb
 // $breadcrumb  = '<ol class="breadcrumb">';
 // $breadcrumb .= '<li><a href="' . base_url() . '">Home</a></li>';
 // $breadcrumb .= '<li class="active">' . $forum->title . '</li>';
 // $breadcrumb .= '</ol>';
 
 foreach ($topics as $topic) {
 
 $topic->author                  = $this->user_model->get_username_from_user_id($topic->user_id);
 $topic->permalink              = $slug . '/' . $topic->slug;
 $topic->posts                  = $this->forum_model->get_posts($topic->id);
 $topic->count_posts            = count($topic->posts);
 $topic->latest_post            = $this->forum_model->get_topic_latest_post($topic->id);
 $topic->latest_post->author    = $this->user_model->get_username_from_user_id($topic->latest_post->user_id);
 
 }
 
 // assign created objects to the data object
 $data->forum      = $forum;
 $data->topics    = $topics;
 // $data->breadcrumb = $breadcrumb;
 
 // load views and send data
 $this->load->view('templates/header');
 $this->load->view('forum/single', $data);
 $this->load->view('templates/footer');
 
 }
 
 } 


Here you have the model:

PHP Code:

public function create_forum($title, $description) {

        $data = array(
            'title' => $title,
            'slug' => strtolower(url_title($title)),
            'description' => $description,
            'created_at' => date('Y-m-j H:i:s'),
            'updated_at' => date('Y-m-j H:i:s')
        );

        return $this->db->insert('forums', $data);
    } 


PHP Code:

public function create_topic($forum_id, $title, $content, $user_id) {

        $data = array(
            'title' => $title,
            'slug' => strtolower(url_title($title)),
            'user_id' => $user_id,
            'forum_id' => $forum_id,
            'created_at' => date('Y-m-j H:i:s'),
            'updated_at' => date('Y-m-j H:i:s'),
        );

        if ($this->db->insert('topics', $data)) {

            $topic_id = $this->db->insert_id();

            return $this->create_post($topic_id, $user_id, $content);
        }

        return false;
    } 


If you miss any other part of the code, just let me know.

Thank you so much for the help.