Code Snippet:

// Create and add the items to the subscription
if( !CreateMonitoredItemsHelper.Execute( { ItemsToCreate: items, TimestampsToReturn: TimestampsToReturn.Both, SubscriptionId: subscription } ) )
{
    addError( "Create monitored items failed with status '" + uaStatus + "'.");
    DeleteSubscriptionsHelper.Execute( { SubscriptionIds: subscription } );
    return( false );
}

Attempt to get ServiceResult was not successfully, because the committed parameter ServiceResult returns 'undefined'.

// Create and add the items to the subscription
var serviceResult;
if( !CreateMonitoredItemsHelper.Execute( { ItemsToCreate: items, TimestampsToReturn: TimestampsToReturn.Both, SubscriptionId: subscription, ServiceResult: serviceResult } ) )
{
    addError( "Create monitored items failed with status '" + serviceResult.StatusCode + "'.");
    DeleteSubscriptionsHelper.Execute( { SubscriptionIds: subscription } );
    return( false );
}

I expect that this parameter could be set in function createMonitoredItems, but there is no code which does use the argument ServiceResult.