From 6eddb195cd4ba389582d9750ec5afc6efcb57d63 Mon Sep 17 00:00:00 2001
From: wmayer <wmayer@users.sourceforge.net>
Date: Tue, 29 Aug 2023 00:52:33 +0200
Subject: [PATCH] Gui: do not call back() on an empty container

Calling back() on an empty container is undefined behaviour: https://en.cppreference.com/w/cpp/container/vector/back
---
 src/Gui/SoFCUnifiedSelection.cpp | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/src/Gui/SoFCUnifiedSelection.cpp b/src/Gui/SoFCUnifiedSelection.cpp
index d7722f3fa4..95924f3bf5 100644
--- a/src/Gui/SoFCUnifiedSelection.cpp
+++ b/src/Gui/SoFCUnifiedSelection.cpp
@@ -1124,9 +1124,14 @@ SoFCSelectionContextBasePtr
 SoFCSelectionRoot::getNodeContext2(Stack &stack, SoNode *node, SoFCSelectionContextBase::MergeFunc *merge)
 {
     SoFCSelectionContextBasePtr ret;
-    auto *back = dynamic_cast<SoFCSelectionRoot*>(stack.back());
-    if(stack.empty() || back == nullptr || back->contextMap2.empty())
+    if (stack.empty()) {
         return ret;
+    }
+
+    auto *back = dynamic_cast<SoFCSelectionRoot*>(stack.back());
+    if (back == nullptr || back->contextMap2.empty()) {
+        return ret;
+    }
 
     int status = 0;
     auto &map = back->contextMap2;