Prestashop error: Trying to access array offset on value of type bool

Question

I developed a custom page within my Prestashop module.
I'm using Prestashop 1.7.7.2 and PHP 7.4.
This is the Controller code:

class MymoduleConfirmemailModuleFrontController extends ModuleFrontController
{

    public $php_self = 'confirmemail';

    public function init()
    {
        parent::init();
    }

    public function initContent()
    {
        parent::initContent();
        $this->setTemplate('confirmemail');
    }

This is the code of the template file:

{extends file='page.tpl'}

{block name='page_header_container'}{/block}

{block name='page_content'}
    <div>TEST</div>
{/block}

When I navigate to corresponding page I receive the following error:
Notice: Trying to access array offset on value of type bool

And the page doesn't display. If I remove the line {extends file='page.tpl'} it displays as expected "TEST".

Following the stack trace, after some debug I found that the problem is in these lines inside classes/Connection.php:

[...]
$sql = 'SELECT SQL_NO_CACHE `id_guest`
        FROM `' . _DB_PREFIX_ . 'connections`
        WHERE `id_guest` = ' . (int) $cookie->id_guest . '
        AND `date_add` > \'' . pSQL(date('Y-m-d H:i:00', time() - 1800)) . '\'
        ' . Shop::addSqlRestriction(Shop::SHARE_CUSTOMER) . '
        ORDER BY `date_add` DESC';
$result = Db::getInstance()->getRow($sql, false);
       
---> if (!$result['id_guest'] && (int) $cookie->id_guest) {
[...]

The problem is that the query returns false because there is no row containing an id_guest with id $cookie->id_guestso the last line throws an error. What am I missing?

Answer 1

You're missing that PS 1.7.7.2 is not compatible with PHP 7.4 yet :

See

https://devdocs.prestashop.com/1.7/basics/installation/system-requirements/

Downgrading to 7.3 should fix the issue.