PartDesign/Feature: add an optional parameter to getBaseObject() to prevent it from throwing exceptions

In most cases getBaseObject() is used with an exception handler which
only detects if it failed but not the reason. This modification allows
to use it without excess exception handlers.
Also add the same parameter to SketchBased::getVerifiedSketch().

src/Mod/PartDesign/Gui/TaskFeatureParameters.cpp

@@ -59,11 +59,11 @@ bool TaskDlgFeatureParameters::accept() {
             throw Base::Exception("Bad object processed in the feature dialog.");
         }
 
-        App::DocumentObject* support = static_cast<PartDesign::Feature*>(feature)->BaseFeature.getValue();
+        App::DocumentObject* previous = static_cast<PartDesign::Feature*>(feature)->getBaseObject(/* silent = */ true );
 
-        if (support) {
+        if (previous) {
             Gui::Command::doCommand(Gui::Command::Gui,"Gui.activeDocument().hide(\"%s\")",
-                    support->getNameInDocument());
+                    previous->getNameInDocument());
         }
 
         Gui::Command::doCommand(Gui::Command::Doc,"App.ActiveDocument.recompute()");
@@ -91,12 +91,7 @@ bool TaskDlgFeatureParameters::reject()
 
     // Find out previous feature we won't be able to do it after abort
     // (at least in the body case)
-    App::DocumentObject* previous;
-    try {
-        previous = feature->getBaseObject(); // throws on errors
-    } catch (const Base::Exception &ex) {
-        previous = 0;
-    }
+    App::DocumentObject* previous = feature->getBaseObject(/* silent = */ true );
 
     // roll back the done things
     Gui::Command::abortCommand();