VLESS inbound: Print invalid UUID string (#5426)

Co-authored-by: RPRX <[email protected]>

proxy/vless/encoding/encoding.go

@@ -10,6 +10,7 @@ import (
 	"github.com/xtls/xray-core/common/protocol"
 	"github.com/xtls/xray-core/common/session"
 	"github.com/xtls/xray-core/common/signal"
+	"github.com/xtls/xray-core/common/uuid"
 	"github.com/xtls/xray-core/proxy"
 	"github.com/xtls/xray-core/proxy/vless"
 )
@@ -91,7 +92,8 @@ func DecodeRequestHeader(isfb bool, first *buf.Buffer, reader io.Reader, validat
 		}
 
 		if request.User = validator.Get(id); request.User == nil {
-			return nil, nil, nil, isfb, errors.New("invalid request user id")
+			u := uuid.UUID(id)
+			return nil, nil, nil, isfb, errors.New("invalid request user id: %s" + u.String())
 		}
 
 		if isfb {