Undefined Index when used with custom entity

When entity reference field is selected with the custom created entity with just one bundle, then bundle selection is not listed in the field settings and hence treats the bundle with same as the entity type name.

However, while listing the select options, it uses entity_get_info() which list all the bundles, but in the field_config table there is no any information of the bundle, i.e target_bundles does not have bundles thats listed in the custom hook_entity_info().

Entity reference field config:

array (
    'target_type' => 'manufacturer',
    'handler' => 'base',
    'handler_settings' => 
    array (
      'target_bundles' => 
      array (
      ),
      'sort' => 
      array (
        'type' => 'property',
        'property' => 'manufacturer_nm',
        'direction' => 'ASC',
      ),
      'behaviors' => 
      array (
        'views-select-list' => 
        array (
          'status' => 0,
        ),
      ),
    ),
    'handler_submit' => 'Change handler',
  ),

Custom Entity Definition

function my_module_entity_info() {
$return = array(
    'MyEntity' => array(
      'label' => t('MyEntity'),
      'controller class' => 'EntityAPIController',
      'base table' => 'my_entity',
      'entity keys' => array(
        'id' => 'eid',
        'uuid' => 'uuid',
        'label' => 'my_entity_name',
      ),
      'uri callback' => 'entity_class_uri',
      'module' => 'my_entity',
      'fieldable' => TRUE,
    	'bundles' => array(
        'my_entity_instance'=> array(
          'label' => 'My Entity',
          'admin' => array(
            'path' => 'admin/structure/my_entity/manage/%bundle_key',
            // This is unique to each bundle.
            'real path' => 'admin/structure/my_entity/manage/manufacturer',
            'bundle argument' => 4,  // Arg 4 is %bundle_key.
            // What ever permission that you've assigned in hook_permissions.
            'access arguments' => array('administer users'),
          ),
        ),
      ),
      'uuid' => TRUE,
    ),
  );
  return $return;
}

As a result it generates

Notice: Undefined index: my_entity in entityreference_options_list() (line 778 of C:\wamp\www\miconnect\sites\all\modules\entityreference\entityreference.module).