From 5ed2850a036970d1eb0cd8f34311c77ca96a1ef9 Mon Sep 17 00:00:00 2001
From: wmayer <wmayer@users.sourceforge.net>
Date: Thu, 28 Apr 2022 23:14:51 +0200
Subject: [PATCH] FEM: work around a crash with vtk9 on export of a
 vtkUnstructuredGrid

---
 src/Mod/Fem/App/PropertyPostDataObject.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/Mod/Fem/App/PropertyPostDataObject.cpp b/src/Mod/Fem/App/PropertyPostDataObject.cpp
index b35bcfd376..5aa9f7ec6c 100644
--- a/src/Mod/Fem/App/PropertyPostDataObject.cpp
+++ b/src/Mod/Fem/App/PropertyPostDataObject.cpp
@@ -313,8 +313,8 @@ void PropertyPostDataObject::SaveDocFile (Base::Writer &writer) const
 #ifdef VTK_CELL_ARRAY_V2
     // Looks like an invalid data object that causes a crash with vtk9
     vtkUnstructuredGrid* dataGrid = vtkUnstructuredGrid::SafeDownCast(m_dataObject);
-    if (dataGrid && dataGrid->GetPiece() < 0) {
-        std::cerr << "PropertyPostDataObject::SaveDocFile: ignore broken vtkUnstructuredGrid\n";
+    if (dataGrid && (dataGrid->GetPiece() < 0 || dataGrid->GetNumberOfPoints() <= 0)) {
+        std::cerr << "PropertyPostDataObject::SaveDocFile: ignore empty vtkUnstructuredGrid\n";
         return;
     }
 #endif