Resolves: tdf#114232 call GetObject() only if IsObject()

 This is a combination of 2 commits.

Resolves: tdf#114232 reset error after unsuccessful GetObject() query

Probably broken already since

    commit 0b21b8b1
    Date:   Wed Oct 6 10:16:27 2010 +0100

        initial commit for vba blob ( not including container_control stuff )

Change-Id: Iecce564851a76921b491ff101365c70883ad7475
(cherry picked from commit 863e269c)

Rather call GetObject() only if IsObject(), tdf#112571 follow-up

Which effectively is what GetObject() internally also does to
determine whether to set an error, so resetting an error here is
moot (or might even hide a nested error?).

Change-Id: I8736d16e386d1833126965538f96aaa1fd73dfd6
(cherry picked from commit d1cd68fa)
Reviewed-on: https://gerrit.libreoffice.org/45904Reviewed-by: Eike Rathke <erack@redhat.com>
Tested-by: Jenkins <ci@libreoffice.org>

basic/source/runtime/methods.cxx

@@ -2461,7 +2461,7 @@ void SbRtl_IsError(StarBASIC *, SbxArray & rPar, bool)
         SbUnoObject* pObj = dynamic_cast<SbUnoObject*>( pVar  );
         if ( !pObj )
         {
-            if ( SbxBase* pBaseObj = pVar->GetObject() )
+            if ( SbxBase* pBaseObj = (pVar->IsObject() ? pVar->GetObject() : nullptr) )
             {
                 pObj = dynamic_cast<SbUnoObject*>( pBaseObj  );
             }