TD: Fix loading project files

With PR 19941 there is a regression where parts of the document
won't be restored. This is caused by overriding the virtual method
handleChangedPropertyType() but not calling the method of the base class.

While searching for a fix another problem showed up where (due to the
incomplete loading) exceptions are thrown but not handled within TD.
Therefore the method recompute() is overridden in DrawView to also handle
OCC exceptions.

src/Mod/TechDraw/App/DrawView.h

@@ -65,6 +65,7 @@ public:
 
     /** @name methods override Feature */
     //@{
+    App::DocumentObjectExecReturn* recompute() override;
     /// recalculate the Feature
     App::DocumentObjectExecReturn *execute() override;
     void onDocumentRestored() override;