This is the error I am getting with my code. 

If possible can anyone help. Thank you i n advance


public with sharing class Casenow {
    @AuraEnabled
  public string topicPickvalue{get;set;} 
  public list<topic> topicList{get; set;}  
  public list<wrapperclass> wrapperelement_for_cases{get;set;}
  public list<wrapperclass> wrapperelement_for_contact{get;set;}
  public list<wrapperclass> wrapperelement_for_opportunity{get; set;}

      
    list<cases> object1 = [select id,name from cases limit 10];
    list<contact> object2 = [select id,name from contact limit 10];
    list<opportunity> object3 = [select id, name from opportunity limit 10];
  public list<wrapperclass> getcaseswrapperret(){
    wrapperelement_for_cases = new list<wrapperclass>();
   for(cases obj1: object1){
    wrapperelement_for_cases.add(new wrapperclass(obj1));
   }
   return wrapperelement_for_cases;
   }
 public list<wrapperclass> getcontactwrapperret(){
    wrapperelement_for_contact = new list<wrapperclass>();
   for(contact obj2: object2){
wrapperelement_for_contact.add(new wrapperclass(obj2));
   }
   return wrapperelement_for_contact;
   }
 public list<wrapperclass> getopportunitywrapperret(){
    wrapperelement_for_opportunity = new list<wrapperclass>();
   for(opportunity obj3: object3){
wrapperelement_for_opportunity.add(new wrapperclass(obj3));
   }
   return wrapperelement_for_opportunity;
   }    
public class wrapperclass{
public cases object_cases_1{get;set;}
public contact object_contact_2{get;set;}
public opportunity object_opportunity_3{get;set;}
    
public wrapperclass(cases obj1){
this.object_cases_1 = (obj1);
}
public wrapperclass(contact obj2){
this.object_contact_2 = (obj2);}

public wrapperclass(opportunity obj3){
this.object_opportunity_3 = (obj3);}    
}
    
}