The part you might be missing is that you're explicitly told "this function returns a value OR and error. You must handle error cases with this function". With

The part you might be missing is that you're explicitly told "this function returns a value OR and error. You must handle error cases with this function". With the try/catch paradigm you never know from the function definition if that is the case. You also know what type the error will be. No need to derive a new class from `Error` and add custom functions to extract the data from your failure case, just pass the data along.