UnassignedReferenceException even though using the null-conditional operator

Question

I\'m getting a UnassignedReferenceException: The variable _Preset of Foo has not been assigned. even though I\'m using the null-conditional operator ?.

Answer 1

Unity has a custom way to check inspector's references against null.

When a MonoBehaviour has fields, in the editor only[1], we do not set those fields to “real null”, but to a “fake null” object. Our custom == operator is able to check if something is one of these fake null objects, and behaves accordingly

They may not have overloaded the null-conditional operator. Your get property returns the "fake null" explaining your unassigned error (and not the NullReferenceException).

The custom null check also comes with a bunch of downsides. It behaves inconsistently with the ?? operator, which also does a null check, but that one does a pure c# null check, and cannot be bypassed to call our custom null check.

I guess the same problem occurs for the null-conditional operator.