Also "_" means the programmer chose to ignore the errors that he knew about at the time. There's no way to know whether the programmer actually considered all

Also "_" means the programmer chose to ignore the errors that he knew about at the time. There's no way to know whether the programmer actually considered all the error cases (they are generally very poorly documented in Go code), and there's no way to know if the called function added errors at some later date. If it's though an interface, there's no way to know that all implementations have the same errors. It's really an 80s-era approach to error handling, and that's bad.