<?php

declare(strict_types=1);

namespace League\Tactician;

/**
 * Marker interface for all Tactician exceptions
 */
interface Exception
{
}

<?php

declare(strict_types=1);

namespace League\Tactician;

use Throwable;

/**
 * Marker interface for all Tactician exceptions
 */
interface Exception extends Throwable
{
}

Make marker interface extend throwable
Make marker interface extend throwable

This makes sure the interface can only be used by exceptions/errors, and
it makes more sense to be catched.