Visual Studio Code PHP Intelephense not hilight probably unset variables

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)