message: Generate report if nullptr
  Summary: Pull Request resolved:
diff: @@ -88,6 +88,7 @@ PacketNumEncodingResult encodeLongHeaderHelper(
  appender.push(originalDstConnId->data(), originalDstConnId->size());
  // Write the retry token
  + assert(token && "token is nullptr");
  appender.insert(*token);
  }
  // defer write of the packet num and length till payload has been computed
  