Calling count() on an EXTRA_LAZY collection throws an exception.
Notice: Undefined index: iUserId in /../vendor/doctrine/lib/Doctrine/ORM/Persisters/OneToManyPersister.php line 142
I've found that this is caused by looking up the fieldName for iUserId on the targetEntity, while it should be looked up at the sourceEntity. The current tests pass because all entities have a mapping of `id' -> $id.
Tests + fix coming up.