hi Marc,
I've created a unit test which is covering all I could think of about projecting a null-marker token defined in a parent entity.. but I couldn't get it to fail.

This is my entire test, could you have a look and suggest changes or make changes please?

https://github.com/hibernate/hibernate-search/commit/005c52502240d94bdb40b2c3a75ef362b6ee882c

Otherwise you must be having a different problem; for sure it shouldn't throw an NPE, I'm opening a different issue for that.