Fix the crash caused by failed downcast of iter

src/graph/executor/algo/SubgraphExecutor.cpp

@@ -100,17 +100,20 @@ folly::Future<Status> SubgraphExecutor::handleResponse(RpcResponse&& resps) {
 
 void SubgraphExecutor::filterEdges(int version) {
   auto iter = ectx_->getVersionedResult(subgraph_->outputVar(), version).iter();
-  auto* gnIter = static_cast<GetNeighborsIter*>(iter.get());
-  while (gnIter->valid()) {
-    const auto& dst = gnIter->getEdgeProp("*", nebula::kDst);
-    if (validVids_.find(dst) == validVids_.end()) {
-      auto edge = gnIter->getEdge();
-      gnIter->erase();
-    } else {
-      gnIter->next();
+  auto* iterPtr = iter.get();
+  if (iterPtr->isGetNeighborsIter()) {
+    auto* gnIter = static_cast<GetNeighborsIter*>(iterPtr);
+    while (gnIter->valid()) {
+      const auto& dst = gnIter->getEdgeProp("*", nebula::kDst);
+      if (validVids_.find(dst) == validVids_.end()) {
+        auto edge = gnIter->getEdge();
+        gnIter->erase();
+      } else {
+        gnIter->next();
+      }
     }
+    gnIter->reset();
   }
-  gnIter->reset();
   ResultBuilder builder;
   builder.iter(std::move(iter));
   ectx_->setVersionedResult(subgraph_->outputVar(), builder.build(), version);

src/graph/executor/query/DataCollectExecutor.cpp

@@ -65,6 +65,9 @@ Status DataCollectExecutor::collectSubgraph(const std::vector<std::string>& vars
   ds.colNames = std::move(colNames_);
   const auto& hist = ectx_->getHistory(vars[0]);
   for (const auto& result : hist) {
+    if (!result.iterRef()->isGetNeighborsIter()) {
+      continue;
+    }
     auto iter = result.iter();
     auto* gnIter = static_cast<GetNeighborsIter*>(iter.get());
     List vertices;

tests/tck/features/bugfix/FixIterCrash.feature

@@ -0,0 +1,23 @@
+# Copyright (c) 2022 vesoft inc. All rights reserved.
+#
+# This source code is licensed under Apache 2.0 License.
+Feature: FixIterCrash
+
+  Scenario: Fix GetNeighborsIter Crash
+    Given an empty graph
+    And having executed:
+      """
+      CREATE SPACE nba_FixIterCrash as nba
+      """
+    And wait 6 seconds
+    And having executed:
+      """
+      USE nba_FixIterCrash
+      """
+    When executing query:
+      """
+      GO from 'Tim Duncan' OVER serve YIELD serve._src AS id |
+      GET SUBGRAPH WITH PROP FROM $-.id
+      YIELD vertices as nodes, edges as relationships
+      """
+    Then the execution should be successful