handler_settings can be undefined when going through ValidReferenceConstraintValidator

When saving an entity with a linky field, the following notice is thrown due to handler_settings being undefined during entity reference field validation.

Partial trace:

Notice: Undefined index: handler_settings in Drupal\linky\Plugin\EntityReferenceSelection\LinkySelection->buildEntityQuery() (line 25 of modules/contrib/linky/src/Plugin/EntityReferenceSelection/LinkySelection.php).
Drupal\linky\Plugin\EntityReferenceSelection\LinkySelection->buildEntityQuery() (Line: 362)
Drupal\Core\Entity\Plugin\EntityReferenceSelection\DefaultSelection->validateReferenceableEntities(Array) (Line: 134)
Drupal\Core\Entity\Plugin\Validation\Constraint\ValidReferenceConstraintValidator->validate(Object, Object) (Line: 196)
Drupal\Core\TypedData\Validation\RecursiveContextualValidator->validateConstraints(Object, '0000000024710cff0000000011de0a7f', Array) (Line: 148)
Drupal\Core\TypedData\Validation\RecursiveContextualValidator->validateNode(Object) (Line: 158)
Drupal\Core\TypedData\Validation\RecursiveContextualValidator->validateNode(Object, Array, 1) (Line: 100)
Drupal\Core\TypedData\Validation\RecursiveContextualValidator->validate(Object, NULL, NULL) (Line: 90)
Drupal\Core\TypedData\Validation\RecursiveValidator->validate(Object) (Line: 132)
Drupal\Core\TypedData\TypedData->validate() (Line: 489)
Drupal\Core\Entity\ContentEntityBase->validate() (Line: 243)
Drupal\Core\Entity\Entity\EntityFormDisplay->validateFormValues(Object, Array, Object) (Line: 1268)