From 75b55658a755a8fcc50d53bfe7e088ea104fda36 Mon Sep 17 00:00:00 2001
From: Kevin Martin <kpmartin@papertrail.ca>
Date: Mon, 31 Mar 2025 15:52:05 -0400
Subject: [PATCH] Check for a null scene object Under certain unusual
 circumstances getSceneGraph can be called when the scene is null, causing a
 native exception when the scene's reference count is incremented. This
 changes the code to return python None in this condition, allowing the
 calling cod eto handle the no-scene case itself.

---
 src/Gui/View3DPy.cpp | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/Gui/View3DPy.cpp b/src/Gui/View3DPy.cpp
index dab66a874b..30eaf2a56a 100644
--- a/src/Gui/View3DPy.cpp
+++ b/src/Gui/View3DPy.cpp
@@ -2135,6 +2135,9 @@ Py::Object View3DInventorPy::getSceneGraph()
 {
     try {
         SoNode* scene = getView3DInventorPtr()->getViewer()->getSceneGraph();
+        if (scene == nullptr) {
+            return Py::None();
+        }
         PyObject* proxy = nullptr;
         proxy = Base::Interpreter().createSWIGPointerObj("pivy.coin", "SoSeparator *", static_cast<void*>(scene), 1);
         scene->ref();