I am trying to add error message 

global class ProductSearchPopupController {
   
    public String query {get; set;}
    public List<PricebookEntry__c> products {get; set;}
    public List<wrapProduct> wrapProductList {get; set;}
    public List<PricebookEntry__c> selectedProduct{get;set;}
    public List<QuoteLineitem__c> quoteLineList{get;set;}
    public List<wrapProduct> selectedWrapperList{get;set;}
    public Boolean normalList{get;set;}
    public Boolean selectedList{get;set;}
    public Boolean block{get;set;}
    public Boolean block1{get;set;}
    public Boolean block2{get;set;}
    public String SalesPrice {get; set;}
    public integer Discount {get; set;}
    public String Quantity {get; set;}
    public String ServiceDate {get; set;}
    Id recordId;
   
    public ProductSearchPopupController(ApexPages.StandardController controller){
        recordId = controller.getId();
        SalesPrice='';
        Discount=0;
        Quantity='';
        ServiceDate='';
        system.debug('recordId '+recordId);
        wrapProductList = new List<wrapProduct>();
        selectedWrapperList = new List<wrapProduct>();
        normalList = true;
        selectedList = false;
        block = true;
        block1 = false;
        block2 = false;
        
    }
   
     public PageReference runQuery1(){
         
        List<PricebookEntry__c> searchResults=[select id, Name, ProductCode__c, Product2Id__r.Product_Description__c,UnitPrice__c, UseStandardPrice__c from PricebookEntry__c];
        if(searchResults.size()>= 0 ){
            
            for(PricebookEntry__c a: searchResults) {
                // As each Account is processed we create a new wrapAccount object and add it to the wrapAccountList
                wrapProductList.add(new wrapProduct(a));
                block = true;
                block1 = true;
                block2 = false;
            }
        }
        return null;
    }
    
    public PageReference runQuery(){
        wrapProductList = new List<wrapProduct>();
        if(query == null || query == ''){
            system.debug('query '+query);
            ApexPages.addmessage(new ApexPages.message(ApexPages.severity.Info,'Please enter Product to search for'));
               runQuery1();
           else if (searchText.length()<2)
 {
 Apexpages.addMessage(new Apexpages.Message(ApexPages.severity.INFO, 'Input box must contain at least two characters')); 
 }
        }

        system.debug('query '+query);
        List<List<PricebookEntry__c>> searchResults=[FIND :query IN ALL FIELDS RETURNING PricebookEntry__c (id, Name, ProductCode__c, Product2Id__r.Product_Description__c,UnitPrice__c, UseStandardPrice__c)];
        if(searchResults[0]!=null){
            for(PricebookEntry__c a: searchResults[0]) {
                // As each Account is processed we create a new wrapAccount object and add it to the wrapAccountList
                wrapProductList.add(new wrapProduct(a));
                block = true;
                block1 = true;  
                block2 = false;

            }
        }
        return null;
    }
    public PageReference ProceedWithSelectedToNextPage(){
        selectedWrapperList = new List<wrapProduct>();
        normalList = false;
        selectedList = true;
        for(wrapProduct selectedWrapObj: wrapProductList){
            system.debug('selectedWrapObj.selected  ---------'+selectedWrapObj.selected);
            if(selectedWrapObj.selected == true)
                selectedWrapperList.add(selectedWrapObj);
        }
        system.debug('selectedWrapperList size ---------'+selectedWrapperList.size());
        PageReference pageRef = new PageReference('/apex/AccountOpportunityTwoPage');
        pageRef.setRedirect(false);
        return pageRef;
    }
    public void processSelected() {
        selectedProduct = new List<PricebookEntry__c>();
        for(wrapProduct wrapProductObj : wrapProductList) {
            if(wrapProductObj.selected == true) {
                selectedProduct.add(wrapProductObj.acc);
                block = false;
                block1 = false;
                block2 = true;
               
            }
        }
    }
   
    public void GoBack() {
        block = true;
        block1 = true;
        block2 = false;
    }
   
    global class wrapProduct{
        public PricebookEntry__c acc {get;set;}
        public Boolean selected {get;set;}
        public wrapProduct(PricebookEntry__c p) {
            this.acc = p;
            this.selected = false;
        }
       
    }
   
    public pagereference saveproduct(){
        List<QuoteLineitem__c> quoteLineList = new  List<QuoteLineitem__c>();
         if(Test.isRunningTest()){
            insertTestData();
        }
        if(!selectedProduct.isEmpty()){
            for(PricebookEntry__c sp:selectedProduct){
                system.debug('sp '+sp);
                QuoteLineitem__c qli = new QuoteLineitem__c();
                qli.QuotesId__c = recordId;
                qli.ListPrice__c = sp.UnitPrice__c;
                qli.UnitPrice__c = sp.UnitPrice__c;
                qli.Product2Id__c = sp.Product2Id__c;    
                if(Discount!=0 || Discount!=null){
                    qli.Discount__c = Discount;
                }
                if(Quantity!=null){
                    qli.Quantity__c = Decimal.valueof(Quantity);
                }
                quoteLineList.add(qli);
            }
            
           
            if(quoteLineList.size() > 0){
                insert quoteLineList;
                PageReference pageRef = new PageReference('https://proseraa.lightning.force.com/lightning/r/Quotes__c/'+recordId+'/view');
                pageRef.setRedirect(true);
                return pageRef;
            }
        }
        return null;
    }
    public void insertTestData(){
        Product2__c testProduct = new Product2__c();
            testProduct.Name='Test product';
            insert testProduct;
            PricebookEntry__c testpbe = new PricebookEntry__c();
                testpbe.Name='Test PriceBookEntry';
                testpbe.UnitPrice__c =123;
                testpbe.Product2Id__c=testProduct.Id;
                insert testpbe;
            selectedProduct.add(testpbe);
    }
    
}