Error: Call to a member function getValue() on null in Drupal\Core\Entity\Plugin\Validation\Constraint\ValidReferenceConstraintValidator->validate() (line 128

Problem/Motivation

Getting this error:
Call to a member function getValue() on null in Drupal\Core\Entity\Plugin\Validation\Constraint\ValidReferenceConstraintValidator->validate() (line 128

Steps to reproduce

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes

Release notes snippet