实现星座图数据的更新

src/render/page/SignalMonitorPage.vue

@@ -27,10 +27,10 @@ import SNRView from '../components/SNRView.vue'
 import { ref, onMounted } from 'vue'
 import { getNMEAObj } from '../api/util'
 
-const BDSNRView = ref()
-const GPSNRView = ref()
-const GLSNRView = ref()
-const GASNRView = ref()
+const BDSNRView = ref(null)
+const GPSNRView = ref(null)
+const GLSNRView = ref(null)
+const GASNRView = ref(null)
 const update = (nmeaStr: string) => {
   const data: any = getMonitoringData(nmeaStr)
   if (!data) return