Warning: strnatcmp() expects parameter 2 to be string, array given in token_asort_tokens() (line 575 of....

There is a problem with the return value of the token_info hook. First, it's not documented properly as this is a hook and it should state this fact in the comment above the function according to the Drupal Standards model. Second, it returns an associative array of arrays which is incorrect. The hook expects a non-associative array, not an associative array.

This issue can be viewed if you click "Flush all Caches" whenever this module is enabled. You will only see these errors when you flush all caches since it's rebuilding the hook cache when you do so. Once cache is cleared, the error does not show up anymore. Here are the errors you will see:

Warning: strnatcmp() expects parameter 2 to be string, array given in token_asort_tokens() (line 575 of modules/token/token.module).
Warning: strnatcmp() expects parameter 2 to be string, array given in token_asort_tokens() (line 575 of modules/token/token.module).
Warning: uasort(): Array was modified by the user comparison function in token_get_info() (line 533 of modules/token/token.module).

The following:

return array(
    'types' => array('user' => $type),
    'tokens' => array('user' => $user),
  );

Should be changed to:

return array(
    'types' => array($type),
    'tokens' => array($user),
  );

I'm sure this is causing problems somewhere since the return values are invalid.