AppSettings.cs

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Configuration;
using System.Globalization;
using System.Text;

namespace UiPath.Shared
{
    public static class AppSettings
    {
        public static string Get(string key)
        {
            var value = ConfigurationManager.AppSettings[key];
            if(value.IsNullOrEmpty())
            {
                throw new ConfigurationErrorsException("Missing key in application settings: " + key);
            }
            return value;
        }

        public static T Get<T>(string key, T defaultValue)
        {
            var value = ConfigurationManager.AppSettings[key];
            return value.IsNullOrEmpty() ? defaultValue : Parse<T>(value);
        }

        public static T Get<T>(string key) =>
            Parse<T>(Get(key));

        private static T Parse<T>(string value) =>
            (T) TypeDescriptor.GetConverter(typeof(T)).ConvertFromInvariantString(value);
    }
}