Operation handles support error queries

操作句柄支持错误信息查询。

Assets/YooAsset/Runtime/AssetSystem/Loader/AssetBundleLoaderBase.cs

@@ -29,6 +29,11 @@ namespace YooAsset
 		/// </summary>
 		public EStatus Status { protected set; get; }
 
+		/// <summary>
+		/// 最近的错误信息
+		/// </summary>
+		public string LastError { protected set; get; }
+
 		/// <summary>
 		/// 是否已经销毁
 		/// </summary>
@@ -139,7 +144,7 @@ namespace YooAsset
 			// 销毁所有Providers
 			foreach (var provider in _providers)
 			{
-				provider.Destory();
+				provider.Destroy();
 			}
 
 			// 从列表里移除Providers