> Composing Errors Codes ... Instead of sprinkling if statements, the error handling can be integrated into the type ... The check for errors is only done once.

That is only a superficial level of composition, if one can call it that at all, that doesn't account for actual composition of errors of different types. The example provided is just encapsulation and therefore orthogonal to the issue of error handling approaches. i.e. in the example, the error handling code is only centralized, not composed.