validate dangerouse construction (#11873)

2 files changed, 11 insertions, 1 deletions

diff --git a/ydb/core/tx/columnshard/engines/scheme/indexes/abstract/program.cpp b/ydb/core/tx/columnshard/engines/scheme/indexes/abstract/program.cpp
index 62ae9bd41a6..8b62f7890c3 100644
--- a/ydb/core/tx/columnshard/engines/scheme/indexes/abstract/program.cpp
+++ b/ydb/core/tx/columnshard/engines/scheme/indexes/abstract/program.cpp
@@ -443,7 +443,12 @@ public:
 
 std::shared_ptr<TDataForIndexesCheckers> TDataForIndexesCheckers::Build(const TProgramContainer& program) {
     AFL_DEBUG(NKikimrServices::TX_COLUMNSHARD)("program", program.DebugString());
-    auto fStep = program.GetSteps().front();
+    auto& steps = program.GetStepsVerified();
+    if (!steps.size()) {
+        AFL_WARN(NKikimrServices::TX_COLUMNSHARD)("event", "no_steps_in_program");
+        return nullptr;
+    }
+    auto fStep = steps.front();
     TNormalForm nForm;
     for (auto&& s : fStep->GetAssignes()) {
         if (!nForm.Add(s, program)) {
diff --git a/ydb/core/tx/program/program.h b/ydb/core/tx/program/program.h
index 3ab18eccc9d..41cd2a06db1 100644
--- a/ydb/core/tx/program/program.h
+++ b/ydb/core/tx/program/program.h
@@ -85,6 +85,11 @@ public:
         }
     }
 
+    const std::vector<std::shared_ptr<NSsa::TProgramStep>>& GetStepsVerified() const {
+        AFL_VERIFY(!!Program);
+        return Program->Steps;
+    }
+
     template <class TDataContainer>
     inline arrow::Status ApplyProgram(std::shared_ptr<TDataContainer>& batch) const {
         if (Program) {