Why doesn't the null coalescing operator (??) work in this situation?

Question

I\'m getting an unexpected NullReferenceException when I run this code, omitting the fileSystemHelper parameter (and therefore defaulting it to nul

Answer 1

Someone else experienced the same problem in this question. Interestingly it is also using a this._field = expression ?? new ClassName(); format. It could be some kind of issue with the debugger, as writing the value out seemed to produce the correct results for them.

Try adding debug/log code to show the value of the field after assignment to eliminate weirdness in the attached debugger.