Fixed crash when the tag prop not exists. (#934)

src/executor/GoExecutor.cpp

@@ -930,7 +930,7 @@ bool GoExecutor::processFinalResult(RpcResponse &rpcResp, Callback cb) const {
     return true;
 }
 
-VariantType GoExecutor::VertexHolder::getDefaultProp(TagID tid, const std::string &prop) const {
+OptVariantType GoExecutor::VertexHolder::getDefaultProp(TagID tid, const std::string &prop) const {
     for (auto it = data_.cbegin(); it != data_.cend(); ++it) {
         auto it2 = it->second.find(tid);
         if (it2 != it->second.cend()) {
@@ -939,7 +939,7 @@ VariantType GoExecutor::VertexHolder::getDefaultProp(TagID tid, const std::strin
     }
 
     DCHECK(false);
-    return "";
+    return Status::Error("Unknown tid");
 }
 
 SupportedType GoExecutor::VertexHolder::getDefaultPropType(TagID tid,

src/executor/GoExecutor.h

@@ -155,7 +155,7 @@ private:
      */
     class VertexHolder final {
     public:
-        VariantType getDefaultProp(TagID tid, const std::string &prop) const;
+        OptVariantType getDefaultProp(TagID tid, const std::string &prop) const;
         OptVariantType get(VertexID id, TagID tid, const std::string &prop) const;
         void add(const storage::cpp2::QueryResponse &resp);
         nebula::cpp2::SupportedType getDefaultPropType(TagID tid, const std::string &prop) const;

src/executor/test/GoTest.cpp

@@ -609,5 +609,22 @@ TEST_F(GoTest, ReferenceVariableInYieldAndWhere) {
     }
 }
 
+TEST_F(GoTest, NotExistTagProp) {
+    {
+        cpp2::ExecutionResponse resp;
+        auto *fmt = "GO FROM %ld OVER serve yield $^.test";
+        auto query = folly::stringPrintf(fmt, players_["Tim Duncan"].vid());
+        auto code = client_->execute(query, resp);
+        ASSERT_NE(cpp2::ErrorCode::SUCCEEDED, code);
+    }
+
+    {
+        cpp2::ExecutionResponse resp;
+        auto *fmt = "GO FROM %ld OVER serve yield serve.test";
+        auto query = folly::stringPrintf(fmt, players_["Tim Duncan"].vid());
+        auto code = client_->execute(query, resp);
+        ASSERT_NE(cpp2::ErrorCode::SUCCEEDED, code);
+    }
+}
 }   // namespace graph
 }   // namespace nebula