basic statistics bugfixes KIKIMR-18323 (#915)

Author: alexd65536

ydb/core/cms/console/console__create_tenant.cpp

@@ -217,6 +217,8 @@ class TTenantsManager::TTxCreateTenant : public TTransactionBase<TTenantsManager
             break;
 
         case Ydb::Cms::CreateDatabaseRequest::kServerlessResources:
+            Tenant->IsExternalStatisticsAggregator = false;
+
             if (!Tenant->IsExternalSubdomain) {
                 return Error(Ydb::StatusIds::PRECONDITION_FAILED,
                     "Cannot create serverless database unless external subdomain is enabled", ctx);

ydb/core/statistics/aggregator/aggregator_impl.cpp

@@ -102,6 +102,10 @@ void TStatisticsAggregator::Handle(TEvStatistics::TEvConnectNode::TPtr& ev) {
         IsPropagateInFlight = true;
     }
 
+    if (!record.NeedSchemeShardsSize()) {
+        return;
+    }
+
     std::vector<TSSId> ssIds;
     ssIds.reserve(record.NeedSchemeShardsSize());
     for (const auto& ssId : record.GetNeedSchemeShards()) {