fix: 截图失败时清空image_payload

src/MaaCore/Controller/AdbController.cpp

@@ -510,6 +510,7 @@ bool asst::AdbController::screencap(cv::Mat& image_payload, bool allow_reconnect
         return true;
     };
 
+    image_payload = {};
     if (m_adb.screencap_method == AdbProperty::ScreencapMethod::UnknownYet) {
         Log.info("Try to find the fastest way to screencap");
         auto min_cost = milliseconds(LLONG_MAX);