common/uuid: fix panic when parsing 32-len invalid UUID string. (#5468)

* common/uuid: fix panic when parsing 32-len invalid UUID string.

* fix: removed typo

proxy/vless/encoding/encoding.go

@@ -93,7 +93,7 @@ func DecodeRequestHeader(isfb bool, first *buf.Buffer, reader io.Reader, validat
 
 		if request.User = validator.Get(id); request.User == nil {
 			u := uuid.UUID(id)
-			return nil, nil, nil, isfb, errors.New("invalid request user id: %s" + u.String())
+			return nil, nil, nil, isfb, errors.New("invalid request user id: " + u.String())
 		}
 
 		if isfb {