Checkbox errors

When creating a new node, I get this error:

Invalid argument supplied for foreach()
/var/www/drupal/includes/form.inc
Line 1206

which is

    foreach ($form['#default_value'] as $key) {
      $value[$key] = 1;
    }

and is coming from domain.module: Line 1560

...
$form['domain']['domain_site'] = array(
        '#type' => 'checkbox',
        '#prefix' => t('<p><b>Publishing options:</b>'),
        '#suffix' => '</p>',
        '#title' => t('Send to all affiliates'),
        '#required' => FALSE,
        '#description' => t('Select if this content can be shown to all affiliates. This setting will override the options below, but you must still select a domain that "owns" this content.'),
        '#default_value' => (isset($form['#node']->nid)) ? $form['#node']->domain_site : variable_get('domain_node_'. $form['#node']->type, $behavior),
      );

$form['domain']['domains'] = array(
        '#type' => empty($format) ? 'checkboxes' : 'select',
        '#title' => t('Publish to'),
        '#options' => $options,
        '#required' => TRUE,
        '#description' => t('Select which affiliates can access this content.'),
        '#default_value' => (isset($form['#node']->nid)) ? $form['#node']->domains : $default,
      );
...

The problem is that #default_value is NULL because (isset($form['#node']->nid)) should be (isset($form['#node']->nid) && $form['#node']->nid > 0) for both $form['domain']['domain_site']['#default_value'] and $form['domain']['domains']['#default_value']