udpmux: Don't log an error if canceled because of shutdown (#2903)

Author: MarcoPolo

p2p/transport/webrtc/udpmux/mux.go

@@ -5,6 +5,7 @@ package udpmux
 import (
 	"bytes"
 	"context"
+	"errors"
 	"fmt"
 	"io"
 	"net"
@@ -143,7 +144,7 @@ func (mux *UDPMux) readLoop() {
 
 		n, addr, err := mux.socket.ReadFrom(buf)
 		if err != nil {
-			if strings.Contains(err.Error(), "use of closed network connection") {
+			if strings.Contains(err.Error(), "use of closed network connection") || errors.Is(err, context.Canceled) {
 				log.Debugf("readLoop exiting: socket %s closed", mux.socket.LocalAddr())
 			} else {
 				log.Errorf("error reading from socket %s: %v", mux.socket.LocalAddr(), err)