Support nesting field collections inside entities referenced by Inline Entity Form

I'm using both the Field Collection module and the Inline Entity Form module.

If I have an entity reference using Inline Entity Form, and the referenced content type includes a Field Collection, the field collection fails to save and I am unable to create the whole node. If I click "Add another item" to add a second field collection item, I get an Ajax error:

Uncaught AjaxError: 
An AJAX HTTP error occurred.
HTTP Result Code: 200
Debugging information follows.
Path: /node/add/news?element_parents=field_testref/form/inline_entity_form/field_test/0&ajax_form=1&_wrapper_format=drupal_ajax
StatusText: OK
ResponseText: 

When this happens, the following messages are logged

Notice: Undefined index: field_collection_item in Drupal\field_collection\Plugin\Field\FieldWidget\FieldCollectionEmbedWidget::validate() (line 188 of /var/www/modules/contrib/field_collection/src/Plugin/Field/FieldWidget/FieldCollectionEmbedWidget.php).

Recoverable fatal error: Argument 1 passed to Drupal\Core\Entity\Entity\EntityFormDisplay::extractFormValues() must implement interface Drupal\Core\Entity\FieldableEntityInterface, null given, called in /var/www/modules/contrib/field_collection/src/Plugin/Field/FieldWidget/FieldCollectionEmbedWidget.php on line 191 and defined in Drupal\Core\Entity\Entity\EntityFormDisplay->extractFormValues() (line 223 of /var/www/core/lib/Drupal/Core/Entity/Entity/EntityFormDisplay.php).

If I attempt to save the node, including the newly created node with Inline Entity Form and the field collection which that node contains, I get a white screen with the generic "The website encountered an unexpected error" message and those same two messages in the logs.

I'm not sure if this would be most appropriate as a feature request, bug report, or support request (I feel like it has aspects of all three), but this is what I'm experiencing and it seems like incorrect behavior.