Метод catch b try в словарях, C#

Language: Layout:

//Rextester.Program.Main is the entry point for your code. Don't change it.
//Microsoft (R) Visual C# Compiler version 2.9.0.63208 (958f2354)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;
using System.Collections.Generic;

namespace Rextester
{
    public class Program
    {
        public static void Main(string[] args)
        {
            //Your code goes here
            Console.WriteLine("Hello, world!");
            
            Dictionary <int, Person> dic= new Dictionary <int, Person>(2);
            dic.Add(1, new Person() {Name ="aa"});
            dic.Add(2, new Person() {Name ="bb"});
           // dic.Add(4,"bb");
            
            foreach (KeyValuePair<int, Person> keyvalue in dic)
            {
                try
                {
                    switch(keyvalue.Key)
                    {
                        case 1:
                    Console.WriteLine(keyvalue.Value.Name);
                    break;
                    
                     case 2:
                    Console.WriteLine(keyvalue.Value);
                    break;
                    }
                }
                catch (ArgumentException)
                {
                    Console.WriteLine("Err");
                }
            }
        }
    }
    
    public class Person
    {
        public string Name {get; set;}
    }
}

Show compiler warnings [ + ] Show input
Compilation time: 0,22 sec, absolute running time: 0,11 sec, cpu time: 0,11 sec, average memory usage: 16 Mb, average nr of threads: 3, absolute service time: 0,36 sec