应用设置函数补全返回值

app/scanner/device_menu.h

@@ -446,17 +446,13 @@ public:
                 else {
                     v.cfg->select_scheme(scheme_name);
                 }
-                applied_scheme_ = scheme_name ? scheme_name : "";
-                if(applied_scheme_.empty())
-                {
-                    std::vector<std::string>    all;
-                    v.cfg->get_all_schemes(all);
-                    applied_scheme_ = all[0];
-                }
+                applied_scheme_ = v.cfg->get_current_scheme_name();
                 v.cfg->save();
                 break;
             }
         }
+
+        return SCANNER_ERR_OK;
     }
 };