Easy CRUD for EntityFramework

Would it be nice if we have a CRUD that works for all tables for EntityFramework without writing repetitive codes? Thanks to Generics, we can finally achieve the tasks.

using SimplePOS.Data;
using SimplePOS.Model;
using System;
using System.Linq;
using System.Linq.Expressions;
using System.Threading.Tasks;

namespace SimplePOS.Helper
{
    public class CRUDHelper
    {
        public static CRUDHelper Instance => new Lazy<CRUDHelper>().Value;

        public DataContext DbContext { get; set; } = null;

        // CREATE
        public async Task<ReturnResult> AddAsync<T>(T item, Expression<Func<object, bool>> WhereEx, string messageIfExists) where T : class
        {
            ReturnResult result = new ReturnResult();

            if (DbContext is null) return result;

            try
            {
                var b = DbContext.Set<T>().Where(WhereEx);

                if (!b.Any())
                {
                    await DbContext.Set<T>().AddAsync(item).ContinueWith(async (a) =>
                    {
                        await DbContext.SaveChangesAsync();
                    });

                    result.Result = true;
                }
                else
                {
                    result.Result = false;
                    result.Message = messageIfExists;
                }
            }
            catch (Exception ex)
            {
                result.Result = false;
                result.Message = ex.Message;
                result.Ex = ex;
            }

            return result;
        }

        // READ with specified parameters
        public ReturnResult Read<T>(Expression<Func<object, bool>> WhereEx) where T : class
        {
            ReturnResult result = new ReturnResult();

            if (DbContext is null) return result;

            try
            {
                var b = DbContext.Set<T>().Where(WhereEx);

                if (b.Any())
                {
                    result.Result = b.ToList();
                }
                else
                {
                    result.Result = false;
                }
            }
            catch (Exception ex)
            {
                result.Result = false;
                result.Message = ex.Message;
                result.Ex = ex;
            }

            return result;
        }

        // READ all
        public ReturnResult ReadAll<T>() where T : class
        {
            ReturnResult result = new ReturnResult();

            if (DbContext is null) return result;

            try
            {
                var b = DbContext.Set<T>().ToList<T>();

                if (b.Any())
                {
                    result.Result = b;
                }
                else
                {
                    result.Result = false;
                }
            }
            catch (Exception ex)
            {
                result.Result = false;
                result.Message = ex.Message;
                result.Ex = ex;
            }

            return result;
        }

        // UPDATE
        public async Task<ReturnResult> UpdateAsync<T>(T item, Expression<Func<object, bool>> WhereEx, string messageIfExists) where T : class
        {
            ReturnResult result = new ReturnResult();

            if (DbContext is null) return result;

            try
            {
                var b = DbContext.Set<T>().Where(WhereEx);

                if (!b.Any())
                {
                    DbContext.Set<T>().Update(item);
                    await DbContext.SaveChangesAsync();

                    result.Result = true;
                }
                else
                {
                    result.Result = false;
                    result.Message = messageIfExists;
                }
            }
            catch (Exception ex)
            {
                result.Result = false;
                result.Message = ex.Message;
                result.Ex = ex;
            }

            return result;
        }

        // DELETE
        public async Task<ReturnResult> DeleteAsync<T>(T item) where T : class
        {
            ReturnResult result = new ReturnResult();

            if (DbContext is null) return result;

            try
            {
                var b = DbContext.Set<T>().Remove(item);
                await DbContext.SaveChangesAsync();

                result.Result = true;
            }
            catch (Exception ex)
            {
                result.Result = false;
                result.Message = ex.Message;
                result.Ex = ex;
            }

            return result;
        }
    }
}

The code is pretty straight forward. One thing to note is to make sure your set the DbContext first
i.e.
CRUDHelper.Instance.DbContext = <your_db_context>;