When executing ServerProjects\Standard\maintree\Subscription Services\Subscription Publish Min 02\Test Cases\004.js stand-alone,
writableTestItems are empty and neither be incremented nor written.

For fixing this I added

    //  We only need the data types of writableTestItem to make UaVariant.Increment( { Item: writableTestItems[i] } ) runnig properly;
    // So make a read request to obtain Value and type.
    // Write the result to writableTestItems
    if( ReadHelper.Execute( { NodesToRead: writableTestItems } ) )
    {
        for( var i=0; i<testItems.length; i++ )
        {
            // keep data type but delete value, i.e. set it to min
            dataType = writableTestItems[i].Value.Value.DataType;
            UaVariant.SetValueMin({Type: dataType, Value: writableTestItems[i].Value.Value});   
        }

    }
    else {
        addError("Unable to get initial values. Aborting.");
        stopCurrentUnit();
    }

in the initialize.js (just before // after each test, rever the values of the test-items back to their initial state
Test.PostTestFunctions.push( __revertOriginalValues );)