com.alicizax.unity/Editor/Misc/ScriptableSingletonUtil.cs

using System;
using AlicizaX;
using UnityEngine;

namespace AlicizaX.Editor
{
    public static class ScriptableSingletonUtil
    {
        public static T Get<T>() where T : ScriptableObject
        {
            string assetType = typeof(T).Name;
            T globalSetting = default;
            string[] globalAssetPaths = UnityEditor.AssetDatabase.FindAssets($"t:{assetType}");
            if (globalAssetPaths.Length > 1)
            {
                foreach (var assetPath in globalAssetPaths)
                {
                    Debug.LogError($"Could not had Multiple {assetType}. Repeated Path: {UnityEditor.AssetDatabase.GUIDToAssetPath(assetPath)}");
                }

                throw new Exception($"Could not had Multiple {assetType}");
            }

            if (globalAssetPaths.Length == 1)
            {
                string path = UnityEditor.AssetDatabase.GUIDToAssetPath(globalAssetPaths[0]);
                globalSetting = UnityEditor.AssetDatabase.LoadAssetAtPath<T>(path);
            }


            if (globalSetting == null)
            {
                Debug.LogError($"Could not found {assetType} asset");
                return null;
            }

            return globalSetting;
        }
    }
}