Error: Call to a member function getTypePlugin() on null in Drupal\content_moderation\StateTransitionValidation->getValidTransitions() - Error on non moderated entities

Problem/Motivation

The module assumes that any entity it accesses via hook will be moderated.
Not all entities on a site are always moderated;

This line:
$transition = $validator->getValidTransitions($entity, $currentUser);

throws a php error even for entity reference fields when rendered anywhere.

Steps to reproduce

Enable the module and try to view a node of non-moderated type

Proposed resolution

Check for moderation/workflow on the accessed entity