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

basic/source/runtime/methods.cxx

@@ -2461,18 +2461,10 @@ void SbRtl_IsError(StarBASIC *, SbxArray & rPar, bool)
         SbUnoObject* pObj = dynamic_cast<SbUnoObject*>( pVar  );
         if ( !pObj )
         {
-            // GetObject() sets error if the variable was not an object, so
-            // remember and reset if it isn't.
-            ErrCode eOld = SbxBase::GetError();
-            if ( SbxBase* pBaseObj = pVar->GetObject() )
+            if ( SbxBase* pBaseObj = (pVar->IsObject() ? pVar->GetObject() : nullptr) )
             {
                 pObj = dynamic_cast<SbUnoObject*>( pBaseObj  );
             }
-            else
-            {
-                SbxBase::ResetError();
-                SbxBase::SetError( eOld );
-            }
         }
         uno::Reference< script::XErrorQuery > xError;
         if ( pObj )