improve logging, improve backend receiver error handling

Author: coder543

backend/receiver/receiver.go

@@ -36,7 +36,7 @@ func receiver(
 			if misc.IsTemporary(err) {
 				continue
 			}
-			if err.Error() != "EOF" {
+			if !misc.SocketClosedError(err) {
 				log.Println("b-receive", err)
 			}
 			return

main.go

@@ -14,6 +14,7 @@ import (
 )
 
 func main() {
+	log.SetFlags(log.LstdFlags | log.Lshortfile)
 	frontend.LaunchAll()
 
 	// launch debug pprof server

misc/misc.go

@@ -2,7 +2,9 @@ package misc
 
 import (
 	"encoding/json"
+	"errors"
 	"fmt"
+	"io"
 	"log"
 	"net"
 )
@@ -29,3 +31,9 @@ func IsTemporary(err error) bool {
 	}
 	return false
 }
+
+func SocketClosedError(err error) bool {
+	return errors.Is(err, io.EOF) ||
+		errors.Is(err, io.ErrClosedPipe) ||
+		errors.Is(err, net.ErrClosed)
+}