From 6f2e1aa993c0a34f9aa539d0466680718ea5f0e2 Mon Sep 17 00:00:00 2001
From: Petru Conduraru <petru@bimvoice.com>
Date: Sat, 29 Aug 2026 12:58:58 +0300
Subject: [PATCH] fix(#6032): guard express::base::as<T>() on null instance

---
 src/ifcparse/express.h | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/ifcparse/express.h b/src/ifcparse/express.h
index 7c6ee795fa..c8327116b9 100644
--- a/src/ifcparse/express.h
+++ b/src/ifcparse/express.h
@@ -132,6 +132,11 @@ class IFC_PARSE_API base {
 
     template <class T>
     T as() const {
+        if (!*this) {
+            // Unresolved or malformed attribute reference (e.g. a step-id
+            // that never resolved to an instance). Never dereference it.
+            return T{};
+        }
         if constexpr (std::is_same_v<entity, T>) {
             if (declaration().as_entity() != nullptr) {
                 return T(data_weak());