I had assumed that there would already be a switch/case because I was going with the example in the code of there being three pseudotypes (bid, ask, and reserved). So it seemed natural to me to use a switch statement to have it execute the code specific to them, and that doing so would be less cluttered than not having the reserved option and instead doing a switch/case (or if/else-if) for bid/ask and a separate try/catch wrapper in case it was a null object.

Edit: to be clear, I agree that the distinction is not nearly as sharp if it's just a case of "is the object valid or not"