initial Reader.HasNext() returns true on empty topic, leading to hangs.

[flowchartsman]

I am creating a reader to stream the last of function output messages to a browser connection:

eader, err := s.pclient.CreateReader(
			pulsar.ReaderOptions{
				Topic:          common.TopicName(common.Tenant, common.NamespaceAgent, uuid),
				StartMessageID: pulsar.EarliestMessageID(),
				Name:           fmt.Sprintf("results_%s_%d", uuid, time.Now().UnixNano()),
			},
		)
		if err != nil {
			respond(w, errorResponse("failed to create reader: "+err.Error()), http.StatusInternalServerError)
			return
		}
		if err := reader.SeekByTime(time.Now().Add(-1 * time.Hour)); err != nil {
			respond(w, errorResponse("failed to seek reader: "+err.Error()), http.StatusInternalServerError)
			return
		}
		defer reader.Close()
		w.Write([]byte(resultsStart))
		for reader.HasNext() {
			msg, err := reader.Next(rctx)
			if err != nil {
				// if we encounter an error, add a dummy dict in case there's a comma, then close the list and add the error to the response
				fmt.Fprintf(w, `{}],"error":"error during results iteration: %s"}`, err)
				f.Flush()
				return
			}

Expected behavior

If there are no results, HasNext() should return false and the handler should proceed.

Actual behavior

Hangs forever.

[flowchartsman]

Resolved in #441