apply_filters with multiple args and multiple add_filter

apply_filters requires you to pass the value to be filtered in the 2nd parameter of this function (after the hook tag name)

$error = apply_filters('check_for_more_errors', $error, $userid);

add_filter('check_for_more_errors', 'error_check_1', 1, 2);

function error_check_1($error, $userid){
    $error[] = get_user_meta($userid, 'Plugin 1 user error', true);
    return $error;
}

add_filter('check_for_more_errors', 'error_check_2', 2, 2);

function error_check_2($error, $userid){
    $error[] = get_user_meta($userid, 'Plugin 2 user error', true);
    return $error;
}