[joeshaw]

OP here. Another commenter pointed out that `errors.Join` didn't exist when I wrote this, but I wouldn't have changed my guidance if it had.

The core issue here is that you want to deal with errors as soon as possible. The async nature of writes to files makes this more challenging. Part of the purpose of this post was to inform people that you don't necessarily always see write errors at write-time, sometimes you see them at close-time and should handle them there. (And sometimes you don't see them at all without fsync.)

Even if you do handle errors in your deferred close, you may be taking other actions that you'd rather not have until the file i/o is completed, and this could leave your program in an inconsistent state. Side effects in Go are common, so this is a practical concern and it is hard to spot and debug.