feat：优化LoadingUtils

lib/utils/loading_utils.dart

@@ -5,7 +5,7 @@ export 'package:flutter_easyloading/flutter_easyloading.dart';
 class LoadingUtils {
   static void showLoading({String? text}) {
     if(EasyLoading.isShow) return;
-    EasyLoading.show(status: text, maskType: EasyLoadingMaskType.black);
+    EasyLoading.show(status: text ?? "加载中...", maskType: EasyLoadingMaskType.black);
   }
 
   static void dismiss() {