[fit]修复bug,

lib/plugins/keyboard_method_handler.dart

@@ -226,10 +226,21 @@ class KeyboardMethodHandler {
   String handleError(dynamic error) {
     if (error is ServerErrorException) {
       AtmobLog.e(tag, "接口请求失败: ${error.message}");
-      return jsonEncode({'code': error.code, 'message': error.message});
+
+      // 抛异常给原生，同时也返回json
+      throw PlatformException(
+        code: error.code.toString(),
+        message: error.message,
+        details: {'code': error.code, 'message': error.message},
+      );
     } else {
       AtmobLog.e(tag, "未知异常: $error");
-      return jsonEncode({'code': -1, 'message': '$error'});
+
+      throw PlatformException(
+        code: "-1",
+        message: error.toString(),
+        details: {'code': -1, 'message': error.toString()},
+      );
     }
   }
 }