+ fix crash when trying to edit broken revolve object

src/Mod/PartDesign/App/FeatureSketchBased.cpp

@@ -234,6 +234,8 @@ const TopoDS_Shape& SketchBased::getSupportShape() const {
 int SketchBased::getSketchAxisCount(void) const
 {
     Part::Part2DObject *sketch = static_cast<Part::Part2DObject*>(Sketch.getValue());
+    if (!sketch)
+        return -1; // the link to the sketch is lost
     return sketch->getAxisCount();
 }
 

src/Mod/PartDesign/Gui/ViewProvider.cpp

@@ -29,7 +29,7 @@
 #include "ViewProvider.h"
 #include <Mod/Part/App/PropertyTopoShape.h>
 #include <Gui/Command.h>
-//#include <Gui/Document.h>
+#include <Base/Exception.h>
 
 using namespace PartDesignGui;
 
@@ -48,7 +48,12 @@ bool ViewProvider::doubleClicked(void)
     std::string Msg("Edit ");
     Msg += this->pcObject->Label.getValue();
     Gui::Command::openCommand(Msg.c_str());
-    Gui::Command::doCommand(Gui::Command::Gui,"Gui.activeDocument().setEdit('%s',0)",this->pcObject->getNameInDocument());
+    try {
+        Gui::Command::doCommand(Gui::Command::Gui,"Gui.activeDocument().setEdit('%s',0)",this->pcObject->getNameInDocument());
+    }
+    catch (const Base::Exception&) {
+        Gui::Command::abortCommand();
+    }
     return true;
 }
 

src/Mod/PartDesign/Gui/ViewProviderRevolution.cpp

@@ -67,6 +67,16 @@ void ViewProviderRevolution::setupContextMenu(QMenu* menu, QObject* receiver, co
 bool ViewProviderRevolution::setEdit(int ModNum)
 {
     if (ModNum == ViewProvider::Default ) {
+        PartDesign::Revolution* pcRevolution = static_cast<PartDesign::Revolution*>(getObject());
+        if (pcRevolution->getSketchAxisCount() < 0) {
+            QMessageBox msgBox;
+            msgBox.setIcon(QMessageBox::Critical);
+            msgBox.setWindowTitle(QObject::tr("Lost link to base sketch"));
+            msgBox.setText(QObject::tr("The object can't be edited because the link to the the base sketch is lost."));
+            msgBox.setStandardButtons(QMessageBox::Ok);
+            msgBox.exec();
+            return false;
+        }
         // When double-clicking on the item for this pad the
         // object unsets and sets its edit mode without closing
         // the task panel