From 693444d4d2c9bd4e6aa32f6930c3576046852275 Mon Sep 17 00:00:00 2001
From: Thomas Krijnen <t.krijnen@gmail.com>
Date: Mon, 13 Nov 2017 14:58:02 +0100
Subject: [PATCH] Fix traversal

---
 src/ifcparse/IfcParse.cpp | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/ifcparse/IfcParse.cpp b/src/ifcparse/IfcParse.cpp
index 1706f94e6b..ec1bef07c3 100644
--- a/src/ifcparse/IfcParse.cpp
+++ b/src/ifcparse/IfcParse.cpp
@@ -1085,7 +1085,14 @@ void IfcFile::traverse(IfcUtil::IfcBaseClass* instance, std::set<IfcUtil::IfcBas
 
 	if (level >= max_level && max_level > 0) return;
 
-	auto attributes = instance->declaration().as_entity()->all_attributes();
+	auto entity = instance->declaration().as_entity();
+	if (!entity) {
+		// This is a simple type instance, don't traverse attributes.
+		return;
+	}
+
+	auto attributes = entity->all_attributes();
+
 	for (unsigned i = 0; i < attributes.size(); ++i) {
 		Argument* arg = instance->data().getArgument(i);