The reason you have many exception types is because handling of different kinds of errors is done in different places. I agree that in practice this is not ofte

The reason you have many exception types is because handling of different kinds of errors is done in different places. I agree that in practice this is not often done, and maybe it is an overdesign. BTW, exceptions don't exactly introduce the colored-function problem, because it's easy to catch an exception, handle the error, and stop the "color chain." In fact, that's the whole idea. With async/sync this either cannot be done, or, if it can, it comes at a significant cost.