[ngrilly]

> I don't like that it's mutable state that is easy to shadow accidentally.

It can't happen. The compiler forbids it: https://play.golang.org/p/65bFHrgGblb

> Also, in a function with a couple of different error types, do you end up checking the error type manually and reacting accordingly, all in one final defer?

If a function needs to check the error returned by another function and act accordingly, then don't use try() and use a if statement.

If we just need to decorate the errors with proper context before returning them to the caller, then we use try everywhere and a single defer statement for the decoration. We can use a single defer statement because we expect that the error context is the same in the whole function. See this comment by Russ Cox: https://github.com/golang/go/issues/32437#issuecomment-50329...

> this would loose proper backtrace information: the backtraces all point to the defer line rather than separate lines for each error

No. In the deferred function, you can get the line of the actual return: https://play.golang.org/p/7MVZupCLh5F