Include handler errors in the log file

[JustAnotherArchivist]

I realised today that many messages only get logged to stderr, not to the log file. In particular, this includes all errors in the handlers, e.g. errors on reading from the storage (i.e. the log.Printf calls in handlers.go). I'd like to suggest having those both on stderr and in the log file (if one is specified).

[aspacca]

I will check @JustAnotherArchivist , thanks for reporting.

[stefanbenten]

I would suggest to chose either stderr or log, but not both.

[aspacca]

We should only rely on the logger instantiated in the cmd package: https://github.com/dutchcoders/transfer.sh/blob/master/cmd/cmd.go#L294

This will either use stdout or the log file if set (

transfer.sh/server/server.go

Lines 160 to 176 in 49c6d7e

	func LogFile(logger *log.Logger, s string) OptionFn {
	return func(srvr *Server) {
	f, err := os.OpenFile(s, os.O_RDWR|os.O_CREATE|os.O_APPEND, 0666)
	if err != nil {
	log.Fatalf("error opening file: %v", err)
	}
	logger.SetOutput(f)
	srvr.logger = logger
	}
	}
	func Logger(logger *log.Logger) OptionFn {
	return func(srvr *Server) {
	srvr.logger = logger
	}
	}

)

The calls to log.Printf etc should be replaced by logger.Printf etc