修复某些情况nativeUrl为undefined导致的异常

assets/middleLayer_for_NJ_lite/script/middleLayerBase.ts

@@ -227,10 +227,11 @@ export abstract class middleLayerBase extends cc.Component {
 		deepDrog(cc.find("Canvas"));
 		// 释放远程加载的资源
 		cc.assetManager.assets.forEach(item => {
-			if(
-				item.nativeUrl.indexOf(`h5template`)==-1 
-				&& item.nativeUrl.indexOf(`dist`)==-1 
-				&& item.nativeUrl.indexOf(`http`)>-1
+			if (
+				item.nativeUrl && 
+				item.nativeUrl.indexOf(`h5template`) == -1
+				&& item.nativeUrl.indexOf(`dist`) == -1
+				&& item.nativeUrl.indexOf(`http`) > -1
 			) {
 				cc.assetManager.releaseAsset(item);
 			}