can't dump contact_form entities with kint

Attempting to dmp() a contact_form entity produces this crash:

The website encountered an unexpected error. Please try again later.
Error: Call to undefined method Drupal\contact\Entity\ContactForm::getIterator() in Drupal\Core\Entity\Plugin\DataType\EntityAdapter->getIterator() (line 170 of core/lib/Drupal/Core/Entity/Plugin/DataType/EntityAdapter.php).

Drupal\Core\Entity\Plugin\DataType\EntityAdapter->getIterator()
iterator_to_array(Object, 1) (Line: 14)
Kint_Parsers_objectIterateable->_parse(Object) (Line: 132)
kintParser::factory(Object, 'typedData') (Line: 475)
kintParser::_parse_object(Object, Object) (Line: 115)
kintParser::factory(Object, '$input') (Line: 234)
[snip]

I've not had a problem with other config entities.