nghttpx: Return -1 if dconn_ is nullptr on push_upload_data_chunk

src/shrpx_downstream.cc

@@ -318,7 +318,7 @@ int Downstream::push_upload_data_chunk(const uint8_t *data, size_t datalen)
   // buffer using push_request_headers().
   if(!dconn_) {
     DLOG(WARNING, this) << "dconn_ is NULL";
-    return 0;
+    return -1;
   }
   request_bodylen_ += datalen;
   return dconn_->push_upload_data_chunk(data, datalen);