My test class is not working:

Apexclass:

public with sharing class OpportunityPDF {

    public Opportunity opp{get;set;}
    public list<OpportunityLineItem> product{get;set;}
    public list<OpportunityLineItem> product1{get;set;}
    public Double total{get;set;}
    public Decimal discount{get;set;}
    public Decimal grandTotal{get;set;}
    public Date Today { get { return Date.today(); }}
    public Date lastDate{get;set;}
    public List<terms_and_conditions__c> termsList{get;set;}
    public List<terms_and_conditions__c> termsList12{get;set;}
    public List<WrapperClassEx> wrapperObj{get;set;}
    public Boolean checkBox{get;set;}
    public Boolean displayPopup {get;set;}
    public set<string> TCNames {get;set;}
    public list<Terms_and_Conditions__c> TRC{get;set;}
  
    public OpportunityPDF(){
            opp = [select id,CreatedBy.Email,Opportunity_Number__c,CreatedBy.Fax,CreatedBy.Phone,Account.Name, Account.BillingCity , Account.BillingCountry , Account.BillingState ,Account.BillingStreet,Account.BillingPostalCode ,Account.Insurance_Company__c ,
                      Contract_Start_Date__c,Contract_Term_Months__c,CloseDate,Payment_Terms__c,TotalOpportunityQuantity,Name,Shipping_Method__c,Shipping_Terms__c    from Opportunity where id = :Apexpages.currentpage().getParameters().get('id')];
       
            product = [select id,Opportunity.Id ,Total__c,Discount,Billing_Frequency__c,Billing_Type__c,UnitPrice,Quantity ,Description,TotalPrice,PricebookEntry.Product2.Name  from OpportunityLineItem where Opportunity.Id  = :opp.id and Billing_Type__c = 'Initial'];
       
            product1 = [select id,Opportunity.Id ,Billing_Frequency__c,Total__c,Billing_Type__c,UnitPrice,Quantity ,Description,TotalPrice,PricebookEntry.Product2.Name  from OpportunityLineItem where Opportunity.Id  = :opp.id and Billing_Type__c = 'Subscription'];
            total = 0.00;
            discount = 0.00; 
            grandTotal = 0.00;
            for(integer i = 0;i<product.size();i++){
                /*Calculate sum of total*/
                total+= product[i].Total__c;
                if(product[i].discount!=Null){
                    discount+= product[i].Total__c-product[i].TotalPrice;   
                }
                    grandTotal= total-discount;
            }
            Date todayDate = System.today();
            Date firstDate = todayDate.toStartOfMonth();
            lastDate = firstDate.addDays(date.daysInMonth(todayDate.year(), todayDate.month()) -1 );
      
            checkBox = false;
            wrapperObj = new List<WrapperClassEx>();
            TRC = new  list<Terms_and_Conditions__c>();
            String decodedUrl = EncodingUtil.urlDecode(Apexpages.currentpage().getParameters().get('TCList'), 'UTF-8');
            set<string> TCNames = new set<string>();
            List<String> TcNamesArray = decodedUrl.split(',,',0);
            for(integer i=0;i<TcNamesArray.size();i++){
                TCNames.add(TcNamesArray[i]);
            }
            termsList = [Select id,name,subject__c,Description__c from Terms_and_Conditions__c where name in :TCNames ];
            for(Terms_and_Conditions__c ter: termsList){
                String termDesc = ter.Description__c;
                termDesc = termDesc.replace('Contract Term',+String.valueOf(opp.Contract_Term_Months__c));
                Datetime myDatetime = (opp.Contract_Start_Date__c).addDays(1);
                String myDatetimeStr = myDatetime.format('MMMM d,  yyyy');
                termDesc = termDesc.replace('Start Date',myDatetimeStr);
                termDesc = termDesc.replace('payment term',+String.valueOf(opp.Payment_Terms__c));
                ter.Description__c = termDesc;
                wrapperObj.add(New WrapperClassEx(ter,checkBox ));
            }       
    }
  
   public Class WrapperClassEx{
   public Terms_and_Conditions__c termObj{get;set;}
   public Boolean checkBox{get;set;}
  
   public WrapperClassEx(Terms_and_Conditions__c termRec,boolean checkBox ){
        this.termObj = termRec;
        this.checkBox = checkBox ;
        if(test.isrunningtest()){
               this.checkBox = true;
            }
     }
   }
}

Test Class:code coverage is 54%....

@isTest
public class OpportunityPDF_TC
{
    static testmethod void method1()
    {
        test.startTest(); 
        CloneOpportunityTrigger__c clone = new CloneOpportunityTrigger__c();
        clone.Trigger_Status__c = true;
        clone.setupownerid = UserInfo.getUserId();
        insert clone;
       
        Terms_and_Conditions__c term = new Terms_and_Conditions__c();
        Boolean bool=true;
        term.Name = 'GPS';
        term.Subject__c = 'GPS';
        term.Description__c = 'des';
        insert term;
       
        Opportunity opp1 = new Opportunity(name='Test Opp 1',StageName = 'Closed Won',CloseDate = Date.newInstance(2009,01,01), Pricebook2Id='01s800000003VCr',
                                                 Renewable__c = true,Contract_Start_Date__c = Date.newInstance(2015,01,01),Contract_Term_Months__c = 1.0);
          
        insert opp1;
       
      

        system.assertEquals(opp1.name,'Test Opp 1');
        ApexPages.CurrentPage().getParameters().put('id',opp1.id);
        String encoded = EncodingUtil.urlEncode('test', 'UTF-8');
        String TRC = Apexpages.currentpage().getParameters().put('test',opp1.name);
        String decodedUrl = EncodingUtil.urlDecode('TRC','UTF-8');
        OpportunityPDF pdf = new  OpportunityPDF();
   
       
        pdf.checkBox = true;
        test.stopTest();
       
    }
  
}

i am getting an error like:

Error Message System.NullPointerException: Argument cannot be null.
Stack Trace (System Code)
Class.OpportunityPDF.<init>: line 50, column 1
Class.OpportunityPDF_TC.method1: line 37, column 1

Could you please help me any one,it is very urgent requiremnt