Error when duplicating parent field of taxonomy_term entity

When copying a vocabulary, I receive this error:

Error: Call to undefined method Drupal\Core\Field\BaseFieldDefinition::createDuplicate() in Drupal\entity_type_clone\Form\CloneEntityTypeData::cloneEntityTypeField() (line 30 of {absolute path to module}/entity_type_clone/src/Form/CloneEntityTypeData.php)

I tracked it down to the 'parent' field on the taxonomy_term entity. I don't pretend to know much about fields and storage but this is what seems to happen:

$field->getTargetBundle()

is called to determine if this is a reference field. Usually this returns nothing for base fields (Drupal\Core\Field\BaseFieldDefinition) but for some reason, the parent field returns the target bundle. However, it is not a base field override (Drupal\Core\Field\Entity\BaseFieldOverride) so it doesn't have access to createDuplicate().

I don't know if it is the proper solution but I just made a special case for taxonomy_term & parent in the conditional. This probably needs a more elegant solution but I'm not very familiar with this code.

I tested out my patch and it skipped trying to copy parent but when the new vocabulary was created, the taxonomy_term__parent table seemed to keep track of parent just fine when I created new terms and sorted them.