Dicebot:
I don't want to argue this in details right now but I think that simply banning null references as valid arrays in program as a whole via contracts is better approach than adding extra level of indirection via Nullable ;)
Nullable is a struct, it doesn't introduce a new leavel of indirection (sometimes it doesn't even add new data). And in the specific situation what's better could only be judged by the OP, because he/she has not shown the code.
Bye, bearophile
