Features bug causing Warning: Invalid argument supplied for foreach() in element_children() (line 6288

When I export my field validation rules to features, I end up with this error.

Warning: Invalid argument supplied for foreach() in element_children() (line 6288 of /Users/jucallme/Sites/systemseed/concern/7.x-1.x/build/includes/common.inc

that is called from clientside_validation_field_validation.module [line] => 30

Here is the export of one of the rules.

/**
 * Implements hook_default_field_validation_rule().
 */
function MY_FEATURE_MODULE_default_field_validation_rule() {
  $export = array();

  $rule = new stdClass();
  $rule->disabled = FALSE; /* Edit this to true to make a default rule disabled initially */
  $rule->api_version = 2;
  $rule->rulename = 'First name can only contain alphabetic characters.';
  $rule->name = 'first_name_alpha_billing';
  $rule->field_name = 'field_cw_profile_firstname';
  $rule->col = 'value';
  $rule->entity_type = 'commerce_customer_profile';
  $rule->bundle = 'billing';
  $rule->validator = 'field_validation_regex_validator';
  $rule->settings = array(
    'data' => '^[a-zA-Z]*$',
    'errors' => 0,
  );
  $rule->error_message = 'First name can only contain alphabetic characters.';
  $export['first_name_alpha_billing'] = $rule;

  return $export;
}