PHP Notice: Trying to get Property of non-object in

Question

I have this error when I try to use PHP 7.1 ( in PHP 5.6 not to give error )

PHP Notice: Trying to get Property of non-object in /home/themes/default/main/rsslib.php on line 18

rsslib.php

<?php

$RSS_Content = array();

function RSS_Tags($item, $type = 1, $channel_name="", $image="")
{
    $y = array();
    $tnl = $item->getElementsByTagName("title");
    $tnl = $tnl->item(0);
    $title = $tnl->firstChild->textContent;

    $tnl = $item->getElementsByTagName("link");
    $tnl = $tnl->item(0);
    $link = $tnl->firstChild->textContent;

    $tnl = $item->getElementsByTagName("pubDate");
    $tnl = $tnl->item(0);
    $date = $tnl->firstChild->textContent;      

    $y["channel"] = $channel_name;
    $y["title"] = $title;
    $y["link"] = $link;
    $y["date"] = $date;     
    $y["type"] = $type;
    $y["image"] = $image;

    return $y;
}


function RSS_Channel( $channel, $key )
{
    global $RSS_Content;

    $items = $channel->getElementsByTagName("item");

    $y = RSS_Tags($channel, 0);
    $channel_name = $y['title'];

    foreach($items as $item)
    {
        $y = RSS_Tags($item, 1, $channel_name, $key);

        array_push($RSS_Content, $y);
    }
}

function RSS_Retrieve( $urls = array() )
{
    global $RSS_Content;
    $RSS_Content = array();

    foreach ( $urls as $key => $url )
    {
        $doc_{$key}  = new DOMDocument();
        $doc_{$key}->load( $url );
        $channels_{$key} = $doc_{$key}->getElementsByTagName("channel");

        foreach( $channels_{$key} as $channel )
        {
            RSS_Channel( $channel, $key );
        }
    }

}

function RSS_RetrieveLinks($url)
{
    global $RSS_Content;

    $doc  = new DOMDocument();
    $doc->load($url);

    $channels = $doc->getElementsByTagName("channel");

    $RSS_Content = array();

    foreach($channels as $channel)
    {
        $items = $channel->getElementsByTagName("item");
        foreach($items as $item)
        {
            $y = RSS_Tags($item, 1);
            array_push($RSS_Content, $y);
        }
    }

}

function RSS_Links($url, $size = 15)
{
    global $RSS_Content;

    $page = "<ul>";

    RSS_RetrieveLinks($url);
    if($size > 0)
        $recents = array_slice($RSS_Content, 0, $size + 1);

    foreach($recents as $article)
    {
        $type = $article["type"];
        if($type == 0) continue;
        $title = $article["title"];
        $link = $article["link"];
        $page .= "<li><a href=\"$link\">$title</a></li>\n";         
    }

    $page .="</ul>\n";

    return $page;
}

function RSS_Display( $urls=array(), $size = 15, $site = 0 )
{
    global $RSS_Content;

    $site = 0;
    $site = (intval($site) == 0) ? 1 : 0;

    RSS_Retrieve( $urls );
    RSS_Sort();

    if($size > 0)
    {
        $recents = array_slice($RSS_Content, 0, $size);
    }

    return $recents;

}

function RSS_Sort()
{
    global $RSS_Content;

    for( $i =0; $i < count( $RSS_Content ); $i++ )
    {
        $array = array();
        for( $j =$i+1; $j < count( $RSS_Content ) - $i; $j++ )
        {
            if( strtotime($RSS_Content[$i]['date']) < strtotime($RSS_Content[$j]['date']) )
            {
                $temp = array(
                    'channel'       =>  $RSS_Content[$i]['channel'],
                    'title'         =>  $RSS_Content[$i]['title'],
                    'link'          =>  $RSS_Content[$i]['link'],
                    'date'          =>  $RSS_Content[$i]['date'],
                    //'description' =>  $RSS_Content[$i]['description'],
                    'image'         =>  $RSS_Content[$i]['image'],
                    'type'          =>  $RSS_Content[$i]['type'],
                );

                $temp2 = array(
                    'channel'       =>  $RSS_Content[$j]['channel'],
                    'title'         =>  $RSS_Content[$j]['title'],
                    'link'          =>  $RSS_Content[$j]['link'],
                    'date'          =>  $RSS_Content[$j]['date'],
                    //'description' =>  $RSS_Content[$j]['description'],
                    'type'          =>  $RSS_Content[$j]['type'],
                    'image'         =>  $RSS_Content[$j]['image'],
                );

                $RSS_Content[$i] = $temp2;
                $RSS_Content[$j] = $temp;

            }
        }
    }
}
?>

Answer 1

Hello, try to do separate that line

$title = $tnl->firstChild->textContent;
$title = $tln->firstChild

and check that this is not null is always a good option

if($title!=NULL){
   $title = $title->textContent;
}