Coalesce operator

The patch for this RFC: https://wiki.php.net/rfc/isset_ternary
OK, so that's executed something like this:

    $temp_variable = foobar(); // actual temporary variables lack names, but for the sake of example...
    var_dump($temp_variable[1] ?? false);

As there's no `1` index, it'll go for the second operand, so your result is `bool(false)`.