@isTest(SeeAllData=true)
public class emailmatchtestclass 
{
    static testMethod void emilmatch(){
        ContactRelationship__c condata=new ContactRelationship__c();
        condata.Name='divya';
        condata.EmailId__c='update234@gmail.com';
        
        insert condata;
        Contact con=new Contact();
        con.Id=condata.ListofContacts__c;
        con.LastName='divya223';
        con.Email='update234@gmail.com';
        con.Email=condata.EmailId__c;
        system.assertEquals(condata.EmailId__c, 'update234@gmail.com');
        con.Opt_out_status__c=true;
        system.assertEquals(condata.EmailId__c, con.Email);
        test.startTest();
        insert con;
        test.stopTest();
        
        
        
    }
}

@isTest(SeeAllData=true)
public class emailmatchtestclass 
{
    static testMethod void emilmatch(){
        ContactRelationship__c condata=new ContactRelationship__c();
        condata.Name='divya';
        condata.EmailId__c='update234@gmail.com';
        
        insert condata;
        Contact con=new Contact();
        con.Id=condata.ListofContacts__c;
        con.LastName='divya223';
        con.Email='update234@gmail.com';
        con.Email=condata.EmailId__c;
        system.assertEquals(condata.EmailId__c, 'update234@gmail.com');
        con.Opt_out_status__c=true;
        system.assertEquals(condata.EmailId__c, con.Email);
        test.startTest();
        insert con;
        test.stopTest();
        
        
        
    }
}

I'am trying to create an apex trigger for conditional autonumber on lead based on lead record type. Getting an error ''execution of BeforeInsert caused by: System.ListException: List index out of bounds: 0''. Can someone help pelase? Thanks.

trigger Autonumber on Lead (before insert, before update) {

    list<Lead> lead= [SELECT Id,Name,Company,Status,Lead_Number__c FROM Lead WHERE Lead_Number__c !=:null AND Lead_Number__c > 0 order by Lead_Number__c desc limit 1];
    decimal maxlead=lead[0].Lead_Number__c;    

    for(Lead Lead:Trigger.new){
        if(lead.RecordTypeId =='0126F000001Cmgn'){
            lead.Lead_Number__c = Integer.valueOf(maxlead)+1;
        }
    }  
}