Visual Studio Code PHP Intelephense not hilight probably unset variables

Question

Visual Studio Code PHP Intelephense not hilight probably unset varuables. How enable hilight probably unset varuables? PhpStorm do it. Code:

        foreach ($paymentCollection as $payment)
        {
            if (!$payment->isInner() && !$payment->getPaySystem()->isCash())
            {
                $summ =  $payment->getSum();
            }
        }

        if ($summ > 0)

$summ not hilighted ($summ = float|array $summ)