Action "Set values to entity variable" does not allow to change fields values of the empty entity variable.

Step to reproduce
1 Create custom entity using ECK module
2 Creat empty entity variable of this entity type
3 Create action "Set values to entity variable" and set fileds values
4 Run action

Expected result
Entity variable has updated.

Actual result
Appears the following error message:
Error: Call to a member function getFieldDefinition() on null in Drupal\business_rules\Plugin\BusinessRulesAction\FillEntityVariableFields->execute() (line 237 of modules\business_rules\src\Plugin\BusinessRulesAction\FillEntityVariableFields.php).