StorageExtension keeps holding reference to model if onPostExecute keeps ending with exception before StorageExtension is executed.

This becomes an issue if you're using Doctrine, executing request for multiple models and clearing EntityManager after each processed model.

The first processed model after such event ends with:
Notice: Undefined index: 000000002300cb730000000045222964 in vendor/doctrine/orm/lib/Doctrine/ORM/UnitOfWork.php:3013