19163: Fixes memory corruption issue (#68)

src/Amalgam/evaluablenode/EvaluableNode.cpp

@@ -423,9 +423,12 @@ void EvaluableNode::InitializeType(EvaluableNode *n, bool copy_labels, bool copy
 
 void EvaluableNode::CopyValueFrom(EvaluableNode *n)
 {
+	//don't do anything if copying from itself (note that some flat hash map structures don't copy well onto themselves)
+	if(n == this)
+		return;
+
 	if(n == nullptr)
 	{
-
 		ClearOrderedChildNodes();
 		ClearMappedChildNodes();
 		//doesn't need an EvaluableNodeManager because not converting child nodes from one type to another
@@ -466,6 +469,10 @@ void EvaluableNode::CopyValueFrom(EvaluableNode *n)
 
 void EvaluableNode::CopyMetadataFrom(EvaluableNode *n)
 {
+	//don't do anything if copying from itself
+	if(n == this)
+		return;
+
 	//copy labels (different ways based on type)
 	if(HasCompactSingleLabelStorage() && n->HasCompactSingleLabelStorage())
 	{

src/Amalgam/evaluablenode/EvaluableNodeTreeFunctions.cpp

@@ -461,12 +461,10 @@ EvaluableNodeReference AccumulateEvaluableNodeIntoEvaluableNode(EvaluableNodeRef
 
 		if(EvaluableNode::IsAssociativeArray(variable_value_node))
 		{
-			new_list->SetMappedChildNodes(value_destination_node->GetMappedChildNodes(), true);
 			new_list->AppendMappedChildNodes(variable_value_node->GetMappedChildNodes());
 		}
 		else if(variable_value_node != nullptr) //treat ordered pairs as new entries as long as not nullptr
 		{
-			new_list->SetMappedChildNodes(value_destination_node->GetMappedChildNodes(), true);
 			//iterate as long as pairs exist
 			auto &vvn_ocn = variable_value_node->GetOrderedChildNodes();
 			for(size_t i = 0; i + 1 < vvn_ocn.size(); i += 2)