retrieve entities only if exist and DO NOT throw error if not found

[nedimdzendzo]

Please have a look and let me know what do you think

[jordonsc]

There's a couple things wrong here:

• You've changed the logic of the retrieve() function, existing code that relies on the retrieve() function throwing an exception (or expecting a valid result) will now fail
• Your return types are inconsistent (and your DocBlock's lie about it)

Instead of changing the logic of retrieve(), rather add a new function to the EntityManager say retrieveEntityOrNull() (similar to Doctrine's getOneOrNullResult() query function) that basically wraps retrieve() and catches a NotFoundException (and only that exception) and returns null instead of the entity.

[jordonsc]

object|null