How to store, change and delete gameobject and it's list element?

So, i'm making a plugin to create/modify/delete gameobjects using custom editor with custom classes list. Everything seems to work fine, but sometimes when i try to remove a class from list(including referenced gameobject which is created on scene), editor gives me an error "Out of range exception". I hope, that somebody can help me out! :) Cheers! :) P.S Here's my source code: Data script:

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using System;
 
 public class PresentationMaker : MonoBehaviour
 {
     //Slide data class
     [System.Serializable]
     public class Slide
     {
         public GameObject Object;
         public int AnInt;
         public float AnFloat;
         public Vector3 AnVector3;
         public Vector3[] AnIntArray = new Vector3[0];
         public bool ExpItem = false;
         public bool Instantiated = false;
     }
 
     //List for slide data class
     public List<Slide> SlideList = new List<Slide>(1);
 
     void AddNew()
     {
         SlideList.Add(new Slide());
     }
 
     void Remove(int i)
     {
         SlideList.RemoveAt(i);
     }
 }

Editor script:

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using UnityEditor;
 using UnityEditorInternal;
 using UnityEditor.SceneManagement;
 
 [InitializeOnLoad]
 public static class ToggleItem
 {
     const string toggleName = "Presentation Maker/Options/Show warning before delete";
     static bool enabled_;
     static ToggleItem()
     {
         ToggleItem.enabled_ = EditorPrefs.GetBool(ToggleItem.toggleName, false);
         EditorApplication.delayCall += () =>
         {
             PerformAction(ToggleItem.enabled_);
         };
     }
 
     [MenuItem(ToggleItem.toggleName)]
     static void ToggleAction()
     {
         PerformAction(!ToggleItem.enabled_);
     }
 
     public static void PerformAction(bool enabled)
     {
         Menu.SetChecked(ToggleItem.toggleName, enabled);
         EditorPrefs.SetBool(ToggleItem.toggleName, enabled);
         ToggleItem.enabled_ = enabled;
         PresentationMakerEditor.swbd = enabled;
         Debug.Log(PresentationMakerEditor.swbd);
     }
 }
 
 [CustomEditor(typeof(PresentationMaker))]
 [CanEditMultipleObjects]
 public class PresentationMakerEditor : Editor
 {
     PresentationMaker PM;
     SerializedObject SerObj;
     SerializedProperty SerProp;
     public List<GameObject> SlidesGOs;
     int ListSize;
     public static bool swbd;
     static string ln = "_______________________________________", pmn = "PresentationManager";
     string InitObjPath = "Prefabs/DefaultSlide";
 
     [MenuItem("Presentation Maker/Create Manager")]
     static void CreateMaker()
     {
         if (GameObject.FindGameObjectWithTag(pmn) != null)
             Debug.LogWarning("Presentation manager already exists!");
         else
         {
             Instantiate(Resources.Load("Prefabs/" + pmn), Vector3.zero, Quaternion.identity);
             GameObject.FindGameObjectWithTag(pmn).name = pmn;
         }
     }
 
     void OnEnable()
     {
         PM = (PresentationMaker)target;
         SerObj = new SerializedObject(PM);
         SerProp = SerObj.FindProperty("SlideList"); // Find the list in script and create a reference
         SlidesGOs = new List<GameObject>();
     }
 
     public override void OnInspectorGUI()
     {
         SerObj.Update();//Update list
         EditorGUILayout.Space();
         EditorGUILayout.Space();
         EditorGUILayout.LabelField("Define slides quantity with a number");
         ListSize = SerProp.arraySize;
         ListSize = EditorGUILayout.IntField("List size", ListSize);
 
         if (ListSize != SerProp.arraySize)
         {
             while (ListSize > SerProp.arraySize)
             {
                 SerProp.InsertArrayElementAtIndex(SerProp.arraySize);
             }
             while (ListSize < SerProp.arraySize)
             {
                 SerProp.DeleteArrayElementAtIndex(SerProp.arraySize - 1);
             }
         }
 
         EditorGUILayout.Space();
 
         //Or add a new item to the List<> with a button
         EditorGUILayout.LabelField("Add a new slide with a button");
 
         if (GUILayout.Button("Add a new slide"))
         {
             PM.SlideList.Add(new PresentationMaker.Slide());
         }
 
         EditorGUILayout.Space();
         EditorGUILayout.Space();
         if (GUILayout.Button("Remove all"))
         {
             if (swbd)
             {
                 if (EditorUtility.DisplayDialog("Warning!", "Are you sure you want to delete all slides?", "Yes", "No"))
                 {
                     ListSize = 0;
                     SerProp.arraySize = 0;
                 }
             }
             else
             {
                 ListSize = 0;
                 SerProp.arraySize = 0;
             }
         }
 
         //Display the list to the inspector window
 
         for (int i = 0; i < SerProp.arraySize; i++)
         {
             SerializedProperty SlideListRef = SerProp.GetArrayElementAtIndex(i);
             SerializedProperty Obj = SlideListRef.FindPropertyRelative("Object");
             SerializedProperty MyInt = SlideListRef.FindPropertyRelative("AnInt");
             SerializedProperty MyFloat = SlideListRef.FindPropertyRelative("AnFloat");
             SerializedProperty MyVect3 = SlideListRef.FindPropertyRelative("AnVector3");
             SerializedProperty MyArray = SlideListRef.FindPropertyRelative("AnIntArray");
             SerializedProperty _ExpItem = SlideListRef.FindPropertyRelative("ExpItem");
             SerializedProperty _Instantiated = SlideListRef.FindPropertyRelative("Instantiated");
             // Hide class instance's values inside foldout
             _ExpItem.boolValue = EditorGUILayout.Foldout(_ExpItem.boolValue, i.ToString() + " slide", true);
             if (_ExpItem.boolValue)
             {
                 EditorGUILayout.BeginVertical("box");
                 EditorGUILayout.LabelField("Automatic Field By Property Type");
                 EditorGUI.BeginChangeCheck();
                 EditorGUILayout.PropertyField(Obj);
                 if (EditorGUI.EndChangeCheck() || PrefabUtility.GetPrefabObject(Obj.objectReferenceValue) != null)
                 {
                     InitObj(_Instantiated, Obj, InitObjPath, i, true);
                 }
                 if (_Instantiated.boolValue == false || Obj.objectReferenceValue == null)
                 {
                     InitObj(_Instantiated, Obj, InitObjPath, i, false);
                 }
                 EditorGUILayout.PropertyField(MyInt);
                 EditorGUILayout.PropertyField(MyFloat);
                 EditorGUILayout.PropertyField(MyVect3);
 
                 // Positions array
                 EditorGUILayout.Space();
                 EditorGUILayout.Space();
                 EditorGUILayout.LabelField("Array Fields");
 
                 if (GUILayout.Button("Add New Index", GUILayout.MaxWidth(130), GUILayout.MaxHeight(20)))
                 {
                     MyArray.InsertArrayElementAtIndex(MyArray.arraySize);
                     MyArray.GetArrayElementAtIndex(MyArray.arraySize - 1).vector3Value = new Vector3(0, 0, 0);
                 }
 
                 for (int n = 0; n < MyArray.arraySize; n++)
                 {
                     EditorGUILayout.PropertyField(MyArray.GetArrayElementAtIndex(n));
                     if (GUILayout.Button("Remove  (" + n.ToString() + ")", GUILayout.MaxWidth(100), GUILayout.MaxHeight(15)))
                     {
                         MyArray.DeleteArrayElementAtIndex(n);
                     }
                 }
 
                 EditorGUILayout.Space();
                 //Remove this index from the List
                 EditorGUILayout.LabelField("Remove an index from the List<> with a button");
                 if (i >= 0 && i <= SlidesGOs.Count)
                 {
                     if (GUILayout.Button("Remove This Index (" + i.ToString() + ")"))
                     {
                         if (swbd)
                         {
                             if (EditorUtility.DisplayDialog("Warning!", "Are you sure you want to delete the slide?", "Yes", "No"))
                             {
                                 SerProp.DeleteArrayElementAtIndex(i);
                                 SlidesGOs.Remove(SlidesGOs[i].gameObject);
                                 DestroyImmediate(SlidesGOs[i].gameObject);
                                 SlidesGOs.RemoveAt(i);
                             }
                         }
                         else
                         {
                             SerProp.DeleteArrayElementAtIndex(i);
                             DestroyImmediate(SlidesGOs[i]);
                             SlidesGOs.RemoveAt(i);
                         }
                     }
                 }
                 EditorGUILayout.EndVertical();
                 EditorGUILayout.Space();
                 EditorGUILayout.Space();
             }
         }
         if (GUI.changed)
             SetObjDirty(PM.gameObject);
         SerObj.ApplyModifiedProperties();
     }
 
     public static void SetObjDirty(GameObject obj)
     {
         EditorUtility.SetDirty(obj);
         EditorSceneManager.MarkSceneDirty(obj.scene);
     }
 
     public void InitObj(SerializedProperty SerPropBool, SerializedProperty SerPropObj, string ObjPath, int index, bool Changed)
     {
         GameObject TempObj;
         SerPropBool.boolValue = true;
         Debug.Log("created");
         if (Changed)
         {
             DestroyImmediate(SlidesGOs[index].gameObject);
             SlidesGOs.RemoveAt(index);
             TempObj = (GameObject)Instantiate(SerPropObj.objectReferenceValue, Vector3.zero, Quaternion.identity);
             SlidesGOs.Insert(index, TempObj);
         }
         else
         {
             TempObj = (GameObject)Instantiate(Resources.Load(ObjPath), Vector3.zero, Quaternion.identity);
             SlidesGOs.Add(TempObj);
         }
         SerPropObj.objectReferenceValue = TempObj;
     }
 }