How to use SHGetFileInfo in unity script to get an icon of a file

I try to get icons of files in unity c# script but get an error

ArgumentException: handle System.Drawing.Icon.FromHandle (IntPtr handle) ShellIcon.GetIcon (System.String fileName, UInt32 flags) (at Assets/_SCRIPTS/MAIN.cs:105) ShellIcon.GetSmallIcon (System.String fileName) (at Assets/_SCRIPTS/MAIN.cs:92) MAIN.GetDesktopIcons () (at Assets/_SCRIPTS/MAIN.cs:42) MAIN.Update () (at Assets/_SCRIPTS/MAIN.cs:52)

I tried the code in a Windows forms c# project and it works. What might be wrong here?

 using UnityEngine;
 using System.Collections;
 using System;
 using System.IO;
 using System.Diagnostics;
 using System.Runtime.InteropServices;
 using System.Drawing;
 
 
 
 [StructLayout(LayoutKind.Sequential)]
 public struct SHFILEINFO
 {
     public IntPtr hIcon;
     public IntPtr iIcon;
     public uint dwAttributes;
     [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 260)]
     public string szDisplayName;
     [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 80)]
     public string szTypeName;
 } ;
 
 
 
 public class MAIN : MonoBehaviour
 {
   
     // Use this for initialization
     void Start()
     {
 
     }
    
     public void GetDesktopIcons()
     {
         string path = Environment.GetFolderPath(Environment.SpecialFolder.Desktop);
         string[] fileEntries = Directory.GetFiles(path);
         foreach (string fileName in fileEntries)
         {
             UnityEngine.Debug.Log(fileName);
             System.Drawing.Icon lIcon;
             lIcon = ShellIcon.GetSmallIcon(fileName);
         }
     }
 
     // Update is called once per frame
     void Update()
     {
 
         if (Input.GetKeyUp(KeyCode.Space))
         {
             GetDesktopIcons();
         }
 
     }
 }
 
 public static class ShellIcon
 {
     [StructLayout(LayoutKind.Sequential)]
     public struct SHFILEINFO
     {
         public IntPtr hIcon;
         public IntPtr iIcon;
         public uint dwAttributes;
         [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 260)]
         public string szDisplayName;
         [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 80)]
         public string szTypeName;
     };
 
     class Win32
     {
         public const uint SHGFI_ICON = 0x100;
         public const uint SHGFI_LARGEICON = 0x0; // 'Large icon
         public const uint SHGFI_SMALLICON = 0x1; // 'Small icon
 
         [DllImport("shell32.dll")]
         public static extern IntPtr SHGetFileInfo(string pszPath, uint dwFileAttributes, ref SHFILEINFO psfi, uint cbSizeFileInfo, uint uFlags);
 
         [DllImport("User32.dll")]
         public static extern int DestroyIcon(IntPtr hIcon);
 
     }
 
     static ShellIcon()
     {
     }
 
     public static Icon GetSmallIcon(string fileName)
     {
         return GetIcon(fileName, Win32.SHGFI_SMALLICON);
     }
 
     public static Icon GetLargeIcon(string fileName)
     {
         return GetIcon(fileName, Win32.SHGFI_LARGEICON);
     }
 
     private static Icon GetIcon(string fileName, uint flags)
     {
         SHFILEINFO shinfo = new SHFILEINFO();
         IntPtr hImgSmall = Win32.SHGetFileInfo(fileName, 0, ref shinfo, (uint)Marshal.SizeOf(shinfo), Win32.SHGFI_ICON | flags);
 
         Icon icon = (Icon)System.Drawing.Icon.FromHandle(shinfo.hIcon).Clone();
         Win32.DestroyIcon(shinfo.hIcon);
         return icon;
     }
 }