fix(interactive): Fix group by with vertex as group key (#4482)

As titled.
Fix #4480

---------

Co-authored-by: liulx20 <[email protected]>

Author: zhanglei1949

flex/engines/graph_db/runtime/execute/ops/retrieve/group_by.cc

@@ -991,6 +991,10 @@ bl::result<ReadOpBuildResultT> GroupByOprBuilder::Build(
       int idx = 0;
       for (const auto& var : vars) {
         auto alias = mappings[idx++].second;
+        if (!var.has_property()) {
+          continue;
+        }
+
         Var var_(graph, ctx, var, VarType::kPathVar);
         if (var_.type() == RTAnyType::kStringValue) {
           TypedKeyCollector<std::string_view>::TypedKeyWrapper wrapper(

flex/interactive/sdk/python/gs_interactive/tests/test_robustness.py

@@ -55,6 +55,7 @@
     "MATCH(a)-[b]->(c) return count(b)",
     "MATCH(a)-[b]->(c) return b",
     "MATCH(a)-[b]->(c) return c.id",
+    "MATCH(a)-[b]->(c) return count(c), c, c.id;",
 ]