In the parallel HTTP fetcher, the error is discarded. This will likely result in a panic when the response is nil. Also, what if it a server locks up? Or the underlying socket never connects and never times out?

I know it’s a toy example, but one must consider all these things in a real system. Go does have good pathways for these concerns, but it’s also easy to do it wrong. I still have to manually reason about access to variables/struct fields from multiple go routines.