disable_breadcrumbs_form_alter is throwing errors for non-node forms that are named '..._node_form'

Not all forms that have '_node_form' in them are node forms. On such forms, an error is thrown:

Notice: Undefined index: #node in disable_breadcrumbs_form_alter() (line 190 of disable_breadcrumbs.module).
Notice: Trying to get property of non-object in disable_breadcrumbs_form_alter() (line 190 of disable_breadcrumbs.module).

A check should be added to make sure that '#node' is set before running logic:

BEFORE:

if (strpos($form_id, "_node_form") !== FALSE &&
in_array($form['#node']->type, $enabled_content_types, TRUE) &&
(user_access('administer breadcrumbs') ||
user_access('disable node breadcrumbs'))) {

AFTER:

if (strpos($form_id, "_node_form") !== FALSE &&
isset($form['#node']) &&
in_array($form['#node']->type, $enabled_content_types, TRUE) &&
(user_access('administer breadcrumbs') ||
user_access('disable node breadcrumbs'))) {