fix: Fixed the bug where methods were added to the MenuItems class on editor start and caused compilation errors

AssetDatabase.LoadAssetAtPath<T>() returns null when it is called on editor start (but not on further scripts reload). Handling this edge case resolved the issue.

Author: SolidAlloy

Editor/MenuItemsGeneration/MenuItemsGenerator.cs

@@ -30,6 +30,13 @@ public static void GenerateClass(MenuItemMethod[] newMethods)
         {
             string classContent = GetClassContent();
 
+            var oldMethods = GenericSOPersistentStorage.MenuItemMethods;
+
+            // Stop if the PersistentStorage asset was not found. It frequently happens on Unity Editor launch, leading
+            // to the false assumption the MenuItemMethods collection is empty.
+            if (oldMethods == null)
+                return;
+
             var oldMethodsSet = new HashSet<MenuItemMethod>(GenericSOPersistentStorage.MenuItemMethods, MenuItemMethod.Comparer);
             var newMethodsSet = new HashSet<MenuItemMethod>(newMethods, MenuItemMethod.Comparer);
 

Editor/Util/GenericSOPersistentStorage.cs

@@ -32,7 +32,7 @@ public class GenericSOPersistentStorage : SingletonScriptableObject<GenericSOPer
         [HideInInspector]
         [SerializeField] private bool _usageExampleTypesAreAdded;
 
-        public static bool IsEmpty => Instance._genericType.Type == null;
+        public static bool IsEmpty => OnlyCreatedInstance == null || OnlyCreatedInstance._genericType.Type == null;
 
         public static TypeReference GenericType => Instance._genericType;
         public static string NamespaceName => Instance._namespaceName;
@@ -41,10 +41,10 @@ public class GenericSOPersistentStorage : SingletonScriptableObject<GenericSOPer
 
         public static MenuItemMethod[] MenuItemMethods
         {
-            get => Instance._menuItemMethods;
+            get => OnlyCreatedInstance == null ? null : OnlyCreatedInstance._menuItemMethods;
             set
             {
-                Instance._menuItemMethods = value;
+                OnlyCreatedInstance._menuItemMethods = value;
                 EditorUtility.SetDirty(Instance);
             }
         }

Runtime/Util/SingletonScriptableObject.cs

@@ -1,5 +1,6 @@
 namespace GenericScriptableObjects.Util
 {
+    using JetBrains.Annotations;
     using UnityEngine;
     using UnityEngine.Assertions;
 #if UNITY_EDITOR
@@ -17,6 +18,11 @@
     public abstract class SingletonScriptableObject<T> : ScriptableObject
         where T : ScriptableObject
     {
+        private const string AssetsFolder = "Assets";
+        private const string ResourcesFolder = "Resources";
+
+        private static readonly string AssetPath = AssetsFolder + '/' + ResourcesFolder + '/' + typeof(T).Name + ".asset";
+
         private static T _instance = null;
 
         public static T Instance
@@ -26,25 +32,7 @@ public static T Instance
                 if (_instance != null)
                     return _instance;
 
-                T instance;
-                const string assetsFolder = "Assets";
-                const string resourcesFolder = "Resources";
-                string assetPath = assetsFolder + '/' + resourcesFolder + '/' + typeof(T).Name + ".asset";
-
-                try
-                {
-#if UNITY_EDITOR
-                    instance = AssetDatabase.LoadAssetAtPath<T>(assetPath);
-#else
-                    instance = Resources.FindObjectsOfTypeAll<T>().FirstOrDefault();
-#endif
-                }
-                catch (UnityException)
-                {
-                    Debug.LogError("GenericScriptableObject.CreateInstance() cannot be called in the field " +
-                              "initializer. Please initialize Generic ScriptableObjects in Awake or Start.");
-                    throw;
-                }
+                T instance = GetInstanceFromAsset();
 
                 if (instance != null)
                 {
@@ -64,16 +52,52 @@ public static T Instance
                 Assert.IsNotNull(_instance);
 
 #if UNITY_EDITOR
-                AssetDatabaseHelper.MakeSureFolderExists(resourcesFolder);
+                AssetDatabaseHelper.MakeSureFolderExists(ResourcesFolder);
 
-                AssetDatabase.CreateAsset(_instance, assetPath);
+                AssetDatabase.CreateAsset(_instance, AssetPath);
                 EditorUtility.SetDirty(_instance);
 #else
                 Debug.Log($"The asset of type {typeof(T)} was not created. Please go to editor and create it.");
 #endif
 
+                Debug.Log("asset was created");
+                return _instance;
+            }
+        }
+
+        public static T OnlyCreatedInstance
+        {
+            get
+            {
+                if (_instance != null)
+                    return _instance;
+
+                _instance = GetInstanceFromAsset();
                 return _instance;
             }
         }
+
+        [CanBeNull]
+        private static T GetInstanceFromAsset()
+        {
+            T instance;
+
+            try
+            {
+#if UNITY_EDITOR
+                instance = AssetDatabase.LoadAssetAtPath<T>(AssetPath);
+#else
+                instance = Resources.FindObjectsOfTypeAll<T>().FirstOrDefault();
+#endif
+            }
+            catch (UnityException)
+            {
+                Debug.LogError("GenericScriptableObject.CreateInstance() cannot be called in the field " +
+                               "initializer. Please initialize Generic ScriptableObjects in Awake or Start.");
+                throw;
+            }
+
+            return instance;
+        }
     }
 }