/**
* @name OrderExtension
* @description This class is provided for you to facilitate the Super Badge
**/
public class OrderExtension {
    
    public Order orderRecord {get;set;}
    public List<OrderItem> orderItemList {get;set;}
    public String selectedFamily {get;set;}
    public List<chartHelper.chartData> pieData {get;set;}
    public Decimal total {get;set;}
    public Map<Id,OrderItem> orderItemMap;
    ApexPages.StandardSetController standardSetController;
    public OrderExtension(ApexPages.StandardController standardController){
        orderRecord = (Order)standardController.getRecord();
        orderItemMap = new Map<id,OrderItem>();
        if ( orderRecord.Id != null ){
            orderRecord = queryOrderRecord(orderRecord.Id);
        }
        resetSsc();
        total = 0;
        for (OrderItem oi : orderRecord.OrderItems) {
            orderItemMap.put(oi.Product2Id, oi);
            if (oi.Quantity > 0) {
                if (null == pieData) {
                    pieData = new List<ChartHelper.ChartData>();
                }
                pieData.add(new chartHelper.ChartData(oi.Product2.Name, oi.Quantity * oi.UnitPrice));
                total += oi.UnitPrice * oi.Quantity;
            }
        }
        PopulateOrderItems();
    }
    void resetSsc() {
        String query = 'SELECT Name, Product2.Family, Product2.Name, Product2Id, UnitPrice, Product2.Quantity_Remaining__c'
            + '  FROM PricebookEntry WHERE IsActive = TRUE';
        if (selectedFamily != null && selectedFamily != Constants.SELECT_ONE) {
            query += ' AND Product2.Family = \'' + selectedFamily + '\'';
        }
        query += ' ORDER BY Name';
        standardSetController = new ApexPages.StandardSetController(Database.getQueryLocator(query));
        standardSetController.setPageSize(Constants.DEFAULT_ROWS);
    }
    //ToDo: Implement your own method to populate orderItemList
    //  that you will call after pagination and/or family selection
    void PopulateOrderItems() {
        orderItemList = new List<OrderItem>();
        for (SObject obj : standardSetController.getRecords()) {
            PricebookEntry pbe = (PricebookEntry)obj;
            
            if (orderItemMap.containsKey(pbe.Product2Id)) {
                orderItemList.add(orderItemMap.get(pbe.Product2Id));
            } else {
                orderItemList.add(new OrderItem(
                    PricebookEntryId=pbe.Id,
                    Product2Id=pbe.Product2Id,
                    UnitPrice=pbe.UnitPrice,
                    Quantity=0,
                    Product2=pbe.Product2
                ));
            }
        }
    }
    /**
* @name OnFieldChange
* @description
**/
    public void OnFieldChange(){
        //ToDo: Implement logic to store the values changed on the page
        for (OrderItem oi : orderItemList) {
            orderItemMap.put(oi.Product2Id, oi);
        }
        //      and populate pieData
        pieData = null;
        total = 0;
        for (OrderItem oi : orderItemMap.values()) {
            if (oi.Quantity > 0) {
                if (null == pieData) {
                    pieData = new List<chartHelper.ChartData>();
                }
                pieData.add(new chartHelper.ChartData(oi.Product2.Name, oi.Quantity * oi.UnitPrice));
                //      and populate total
                total += oi.UnitPrice * oi.Quantity;
            }
        }
    }
    /**
* @name SelectFamily
* @description
**/
    public void SelectFamily(){
        //ToDo: Implement logic to filter based on the selected product family
        resetSsc();
        PopulateOrderItems();
    }
    /**
* @name Save
* @description
**/
    public void Save(){
        //ToDo: Implement logic to save the Order and populated OrderItems
        System.Savepoint sp = Database.setSavepoint();
        try {
            if (null == orderRecord.Pricebook2Id) {
                orderRecord.Pricebook2Id = Constants.STANDARD_PRICEBOOK_ID;
            }
            upsert orderRecord;
            List<OrderItem> orderItemsToUpsert = new List<OrderItem>();
            List<OrderItem> orderItemsToDelete = new List<OrderItem>();
            for (OrderItem oi : orderItemList) {
                if (oi.Quantity > 0) {
                    if (null == oi.OrderId) {
                        oi.OrderId = orderRecord.Id;
                    }
                    orderItemsToUpsert.add(oi);
                } else if (oi.Id != null) {
                    orderItemsToDelete.add(oi);
                }
            }
            upsert orderItemsToUpsert;
            delete orderItemsToDelete;
        } catch (Exception e) {
            Database.rollback(sp);
            apexPages.addMessage(new ApexPages.message(ApexPages.Severity.INFO,Constants.ERROR_MESSAGE));
        }
    }
    /**
* @name First
* @description
**/
    public void First(){
        standardSetController.first();
        PopulateOrderItems();
    }
    /**
* @name Next
* @description
**/
    public void Next(){
        standardSetController.next();
        PopulateOrderItems();
    }
    
    
    /**
* @name Previous
* @description
**/
    public void Previous(){
        standardSetController.previous();
        PopulateOrderItems();
    }
    /**
* @name Last
* @description
**/
    public void Last(){
        standardSetController.last();
        PopulateOrderItems();
    }
    /**
* @name GetHasPrevious
* @description
**/
    public Boolean GetHasPrevious(){
        return standardSetController.getHasPrevious();
    }
    
    /**
* @name GetHasNext
* @description
**/
    public Boolean GetHasNext(){
        return standardSetController.getHasNext();
    }
    
    /**
* @name GetTotalPages
* @description
**/
    public Integer GetTotalPages(){
        return (Integer)Math.ceil(standardSetController.getResultSize() / (Decimal)Constants.DEFAULT_ROWS);
    }
    
    /**
* @name GetPageNumber
* @description
**/
    public Integer GetPageNumber(){
        return standardSetController.getPageNumber();
    }
    
    /**
* @name GetFamilyOptions
* @description
**/
    public List<SelectOption> GetFamilyOptions() {
        List<SelectOption> options = new List<SelectOption>{
            new SelectOption(Constants.SELECT_ONE, Constants.SELECT_ONE)
                };
                    
                    for (Schema.PicklistEntry ple : Constants.PRODUCT_FAMILY) {
                        options.add(new SelectOption(ple.getValue(), ple.getLabel()));
                    }
        return options;
    }
    
    /**
* @name QueryOrderRecord
* @description
**/
    public static Order QueryOrderRecord(Id orderId){
        return [
            SELECT Id, AccountId, EffectiveDate, Name, Status, Pricebook2Id,
            (
                SELECT Id, OrderId, Quantity, UnitPrice, PricebookEntryId, Product2Id,
                Product2.Name, Product2.Family, Product2.Quantity_Remaining__c
                FROM OrderItems
            )
            FROM Order
            WHERE Id = :orderId
        ];
    }
}

Getting the below error message on the "Advanced Apex Specialist" on the last step. Had made sure all test classes are covered and OrderExtension works as expected and there are more than 12 products created. I tried to delete the existing data on the system and recreated it, Very likely that causes the below error message. Have anyone got the similar error message? Would appreciate any suggestions to solve it.

Challenge Not yet complete... here's what's wrong: 
Ensure that you have at least 12 products created and that OrderExtension is still working as specified in the earlier challenge.