I think the hard part of handling all error cases like that is not the actual handling of the error cases, but making your code well structured enough that at a

I think the hard part of handling all error cases like that is not the actual handling of the error cases, but making your code well structured enough that at any given place, you can actually enumerate all possible errors in a reasonably small list and so that you actually have a reasonable way of handling each error. In poorly structured code, all possible errors could often include just about anything and for many of the errors you will have no reasonable way of handling them.