server/service, livequery: Check totals Load for nil (#1802)

Matches status, if there are no results (yet) this bombs as the
the interface value is nil.

server/service/client_live_query.go

@@ -43,7 +43,11 @@ func (h *LiveQueryResultsHandler) Results() <-chan kolide.DistributedQueryResult
 
 // Totals returns the current metadata of hosts targeted by the query
 func (h *LiveQueryResultsHandler) Totals() *targetTotals {
-	return h.totals.Load().(*targetTotals)
+	t := h.totals.Load()
+	if t != nil {
+		return t.(*targetTotals)
+	}
+	return nil
 }
 
 func (h *LiveQueryResultsHandler) Status() *campaignStatus {