From 9f03a78652daf03adbd8cfb50f28b4431d503e9b Mon Sep 17 00:00:00 2001
From: Stinkfist0 <stinkfist0@gmail.com>
Date: Wed, 18 Jul 2018 14:28:48 +0300
Subject: [PATCH] ColladaSerializer::differentiateSlabTypes:
 IfcSlab.PredefinedType is optional so check for its existence.

https://github.com/Tridify/IfcOpenShell/commit/c4f426392cfc021b8a9c617f21d258759b289d6a#diff-cca49440331fb4c1363204028192c459
---
 src/ifcconvert/ColladaSerializer.cpp | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/ifcconvert/ColladaSerializer.cpp b/src/ifcconvert/ColladaSerializer.cpp
index 99004d5e50..1347aa4f5e 100644
--- a/src/ifcconvert/ColladaSerializer.cpp
+++ b/src/ifcconvert/ColladaSerializer.cpp
@@ -413,8 +413,11 @@ void ColladaSerializer::ColladaExporter::write(const IfcGeom::TriangulationEleme
 
 std::string ColladaSerializer::differentiateSlabTypes(const IfcSchema::IfcSlab* slab)
 {
-    switch (slab->PredefinedType())
-    {
+    if (!slab->hasPredefinedType()) {
+        return "_Unknown";
+    }
+
+    switch (slab->PredefinedType()) {
     case IfcSlabTypeEnum::IfcSlabType_FLOOR: return "_Floor";
     case IfcSlabTypeEnum::IfcSlabType_ROOF: return "_Roof";
     case IfcSlabTypeEnum::IfcSlabType_LANDING: return "_Landing";