From 88bd341ad2da7399719d350bf9f715297d8d9f33 Mon Sep 17 00:00:00 2001
From: wmayer <wmayer@users.sourceforge.net>
Date: Sat, 3 Jun 2017 13:46:05 +0200
Subject: [PATCH] fixes #0002926: Trying to access Part.Shape.children() before
 doc.recompute() crashes the whole program

---
 src/Mod/Part/App/TopoShapePyImp.cpp | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/Mod/Part/App/TopoShapePyImp.cpp b/src/Mod/Part/App/TopoShapePyImp.cpp
index 518103c330..8810dba798 100644
--- a/src/Mod/Part/App/TopoShapePyImp.cpp
+++ b/src/Mod/Part/App/TopoShapePyImp.cpp
@@ -1163,7 +1163,12 @@ PyObject* TopoShapePy::childShapes(PyObject *args)
         return NULL;
 
     try {
-        TopoDS_Iterator it(getTopoShapePtr()->getShape(),
+        const TopoDS_Shape& shape = getTopoShapePtr()->getShape();
+        if (shape.IsNull()) {
+            PyErr_SetString(PyExc_ValueError, "Shape is null");
+            return NULL;
+        }
+        TopoDS_Iterator it(shape,
             PyObject_IsTrue(cumOri) ? Standard_True : Standard_False,
             PyObject_IsTrue(cumLoc) ? Standard_True : Standard_False);
         Py::List list;