PHP retrieve array key safely, while waiting for the ?? operator

gistfile1.php

function safe($array)
{
    return function($key, $fallback) use ($array)
    {
        if(!is_array($key))
        {
            return isset($array[$key]) ? $array[$key] : $fallback;
        }

        if(!isset($array[$key[0]]))
        {
            return $fallback;
        }

        $path = $array;

        foreach($key as $keyVal)
        {
            if(!isset($path[$keyVal])) {
                $path = $fallback;
                break;
            }

            $path = $path[$keyVal];
        }

        return $path;
    };
}

/*
  Use:
  $safe = safe($array);
  $value = $safe('key', 'value not found');
  
  For nested keys:
  $safe = safe($array);
  $value = $safe(['key1', 0, 'key3'], 'value not found');
*/