Missing argument 1 for hashcash_get_hashcash()

Using latest stable 6.x-2.1 build I noticed this error occasionally in my site's log:

Missing argument 1 for hashcash_get_hashcash() in /home/.katona/davereid20/drupal-6/sites/all/modules/hashcash/hashcash.module on line 70.

I suspect it has something to do with the hook_menu entry because it does not enforce that there must be a argument passed to hashcash_get_hashcash():

function hashcash_menu(){
  ...
  $items['hashcash'] = array(
    'title' => 'Get Hashcash',
    'description' => 'Returns the start part of a hashcash string',
    'page callback' => 'hashcash_get_hashcash',
    'access arguments' => array('access content'),
    'type' => MENU_CALLBACK
  );
  ...
}

function hashcash_get_hashcash($form_id){
 ...
}

If the $form_id isn't mandatory, then you should add a default value to it like the following:

function hashcash_get_hashcash($form_id = ''){
 ...
}

If the $form_id parameter must *always* be present, then you should use something more like the following:

function hashcash_menu(){
  ...
  $items['hashcash/%'] = array(
    'title' => 'Get Hashcash',
    'description' => 'Returns the start part of a hashcash string',
    'page callback' => 'hashcash_get_hashcash',
    'page arguments' => array(1),
    'access arguments' => array('access content'),
    'type' => MENU_CALLBACK
  );
  ...
}

I'm guessing the latter is probably the preferred option since it doesn't make sense if $form_id is always desired.