From 43e8c2174350808b44656618ff8cb0c6f3e49b05 Mon Sep 17 00:00:00 2001
From: wmayer <wmayer@users.sourceforge.net>
Date: Mon, 23 Jan 2017 19:06:48 +0100
Subject: [PATCH] issue #0002816: Trimming tool crashes

---
 src/Mod/Sketcher/App/PropertyConstraintList.h   | 7 +++++--
 src/Mod/Sketcher/Gui/TaskSketcherConstrains.cpp | 6 ++++++
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/src/Mod/Sketcher/App/PropertyConstraintList.h b/src/Mod/Sketcher/App/PropertyConstraintList.h
index 17b67ec26182..e8f580208907 100644
--- a/src/Mod/Sketcher/App/PropertyConstraintList.h
+++ b/src/Mod/Sketcher/App/PropertyConstraintList.h
@@ -86,7 +86,11 @@ class SketcherExport PropertyConstraintList : public App::PropertyLists
     */
     void setValues(const std::vector<Constraint*>&);
 
-    /// index operator
+    /*!
+     Index operator
+     \note If the geometry is invalid then the index operator
+           returns null. This must be checked by the caller.
+    */
     const Constraint *operator[] (const int idx) const {
         return invalidGeometry ? 0 : _lValueList[idx];
     }
@@ -112,7 +116,6 @@ class SketcherExport PropertyConstraintList : public App::PropertyLists
     void acceptGeometry(const std::vector<Part::Geometry *> &GeoList);
     void checkGeometry(const std::vector<Part::Geometry *> &GeoList);
     bool scanGeometry(const std::vector<Part::Geometry *> &GeoList) const;
-    bool isGeometryInvalid(){return invalidGeometry;}
 
     /// Return status of geometry for better error reporting
     bool hasInvalidGeometry() const { return invalidGeometry; }
diff --git a/src/Mod/Sketcher/Gui/TaskSketcherConstrains.cpp b/src/Mod/Sketcher/Gui/TaskSketcherConstrains.cpp
index e8934d1f338d..51549970bb0c 100644
--- a/src/Mod/Sketcher/Gui/TaskSketcherConstrains.cpp
+++ b/src/Mod/Sketcher/Gui/TaskSketcherConstrains.cpp
@@ -102,6 +102,12 @@ class ConstraintItem : public QListWidgetItem
 
         const Sketcher::Constraint * constraint = sketch->Constraints[ConstraintNbr];
 
+        // it can happen that the geometry of the sketch is tmp. invalid and thus
+        // the index operator returns null.
+        if (!constraint) {
+            return QVariant();
+        }
+
         if (role == Qt::EditRole) {
             if (value.isValid())
                 return value;