IGNIETFERRO-2059: Fix use-after-free error in the TDqExecuter (#4568)

Author: ubyte

ydb/library/yql/providers/dq/actors/executer_actor.cpp

@@ -99,9 +99,9 @@ class TDqExecuter: public TRichActor<TDqExecuter>, NYql::TCounters {
 
     Yql::DqsProto::TWorkerFilter GetPragmaFilter() {
         Yql::DqsProto::TWorkerFilter pragmaFilter;
-        if (Settings->WorkerFilter.Get()) {
+        if (const auto& filter = Settings->WorkerFilter.Get(); filter.Defined()) {
             try {
-                TStringInput inputStream1(Settings->WorkerFilter.Get().GetOrElse(""));
+                TStringInput inputStream1(*filter);
                 ParseFromTextFormat(inputStream1, pragmaFilter);
             } catch (...) {
                 YQL_CLOG(INFO, ProviderDq) << "Cannot parse filter pragma " << CurrentExceptionMessage();