Decompililing Unity Assembly-CSharp IEnumerator

Hi! I decompiled some code from my old Unity project. i used dotPeek to decomile my code and almost everything worked great! except this code:

 [DebuggerHidden]
   private IEnumerator EndShield()
   {
     // ISSUE: object of a compiler-generated type is created
     return (IEnumerator) new ShieldPowerup.\u003CEndShield\u003Ec__Iterator4()
     {
       \u003C\u003Ef__this = this
     };
   }

Whole decompiled Script:

 using System.Collections;
 using System.Collections.Generic;
 using System.Diagnostics;
 using UnityEngine;
 
 public class ShieldPowerup : BasePowerup
 {
   private float RandomShieldTimer;
   private GamePlayManager Manager;
 
   protected override void ActivatePowerup(Collider2D Player, GamePlayManager Manager)
   {
     this.Manager = Manager;
     this.RandomShieldTimer = 10f;
     this.SetShields(true);
     this.StartCoroutine("EndShield");
     this.Graphic.SetActive(false);
   }
 
   private void SetShields(bool State)
   {
     using (List<HitObject>.Enumerator enumerator = this.Manager.GetHitObjects().GetEnumerator())
     {
       while (enumerator.MoveNext())
         enumerator.Current.toggleShield(State);
     }
   }
 
   [DebuggerHidden]
   private IEnumerator EndShield()
   {
     // ISSUE: object of a compiler-generated type is created
     return (IEnumerator) new ShieldPowerup.\u003CEndShield\u003Ec__Iterator4()
     {
       \u003C\u003Ef__this = this
     };
   }
 
   private void StopShield()
   {
     this.SetShields(false);
     Object.Destroy((Object) this.gameObject);
   }
 }
 

How ti fix this code? please help me