From d76124b61e35d3ce7ffec128bf3c07756d7e79a3 Mon Sep 17 00:00:00 2001
From: wmayer <wmayer@users.sourceforge.net>
Date: Fri, 9 Oct 2020 18:54:57 +0200
Subject: [PATCH] Part: [skip ci] fix crash when trying to convert null shape
 to nurbs

---
 src/Mod/Part/App/TopoShape.cpp | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/Mod/Part/App/TopoShape.cpp b/src/Mod/Part/App/TopoShape.cpp
index 014c12c8d7..f954552dcc 100644
--- a/src/Mod/Part/App/TopoShape.cpp
+++ b/src/Mod/Part/App/TopoShape.cpp
@@ -3067,6 +3067,9 @@ TopoDS_Shape TopoShape::mirror(const gp_Ax2& ax2) const
 
 TopoDS_Shape TopoShape::toNurbs() const
 {
+    if (this->_Shape.IsNull())
+        Standard_Failure::Raise("Cannot convert null shape to NURBS");
+
     BRepBuilderAPI_NurbsConvert mkNurbs(this->_Shape);
     return mkNurbs.Shape();
 }