From 52bc770ebf3f5e28044c82108ef071876afb32d3 Mon Sep 17 00:00:00 2001
From: Lukas Matena <lukasmatena@seznam.cz>
Date: Wed, 28 Jun 2023 15:03:02 +0200
Subject: [PATCH] Fix of #10890 (crash when switching light/dark mode with
 Height Range Modifier active)

---
 src/slic3r/GUI/GUI_ObjectLayers.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/slic3r/GUI/GUI_ObjectLayers.cpp b/src/slic3r/GUI/GUI_ObjectLayers.cpp
index 6f6ec523808..4727c6d30b1 100644
--- a/src/slic3r/GUI/GUI_ObjectLayers.cpp
+++ b/src/slic3r/GUI/GUI_ObjectLayers.cpp
@@ -283,7 +283,7 @@ void ObjectLayers::sys_color_changed()
         if (item->IsSizer()) {// case when we have editor with buttons
             for (size_t btn : {2, 3}) { // del_btn, add_btn
                 wxSizerItem* b_item = item->GetSizer()->GetItem(btn);
-                if (b_item->IsWindow()) {
+                if (b_item && b_item->IsWindow()) {
                     auto button = dynamic_cast<PlusMinusButton*>(b_item->GetWindow());
                     if (button != nullptr)
                         button->sys_color_changed();