Minor difference in behavior between +/-

SELECT NULL - date '2023-01-05';
-> result is null
SELECT NULL + date '2023-01-05';
-> result is [42725] ERROR: operator is not unique: unknown + date Hint:
Could not choose a best candidate operator. You might need to add explicit
type casts. Position: 13

I would expect both of those to be null.

Thanks,
Ryan