code: func handleError(err error, options *gbuild.Options, browserErrors *bytes.Buffer) int {
  	switch err := err.(type) {
  	case nil:
  		return 0
  	case compiler.ErrorList:
  		for _, entry := range err {
  			printError(entry, options, browserErrors)
  		}
  		return 1
  	case *exec.ExitError:
  		return err.Sys().(syscall.WaitStatus).ExitStatus()
  	default:
  		printError(err, options, browserErrors)
  		return 1
  	}
  }
docs: // handleError handles err and returns an appropriate exit code.
  // If browserErrors is non-nil, errors are written for presentation in browser.