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

basic/source/runtime/methods.cxx

@@ -2461,10 +2461,18 @@ 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() )
             {
                 pObj = dynamic_cast<SbUnoObject*>( pBaseObj  );
             }
+            else
+            {
+                SbxBase::ResetError();
+                SbxBase::SetError( eOld );
+            }
         }
         uno::Reference< script::XErrorQuery > xError;
         if ( pObj )