Fix fuzz test error.

For a FETCH, if payload length is zero, just skip to the next object. It cannot be an Object Status.

Repro now succeeds.

PiperOrigin-RevId: 881988879

quiche/quic/moqt/moqt_parser.cc

diff --git a/quiche/quic/moqt/moqt_parser.cc b/quiche/quic/moqt/moqt_parser.cc
index 8b52e6e..38e1743 100644
--- a/quiche/quic/moqt/moqt_parser.cc
+++ b/quiche/quic/moqt/moqt_parser.cc
@@ -1518,7 +1518,7 @@
           metadata_.object_status = MoqtObjectStatus::kNormal;
           next_input_ = kData;
         } else {
-          next_input_ = kStatus;
+          next_input_ = type_.IsFetch() ? kSerializationFlags : kStatus;
         }
       }
       return;