🐞 fix: 处理无数据情况，确保图表数据清空

ruoyi-ui/src/views/dataStatistics/realtime/left-top.vue

@@ -80,6 +80,9 @@ export default {
             const seriesData = res.rows.map((item) => parseFloat(item.ds));
             this.chartData.Xdata = axisData;
             this.chartData.Ydata = seriesData;
+          } else {
+            this.chartData.Xdata = [];
+            this.chartData.Ydata = [];
           }
         });
       }