fix typo

src/components/FaceRecognition/FaceRecognition.vue

@@ -72,7 +72,7 @@ export default {
           this.$refs.video.srcObject.getTracks().forEach(function(track) {
             track.stop();
           });
-          this.$refs.video.srcObject.srcObject = null;
+          this.$refs.video.srcObject = null;
         }
       } else {
         this.openCamera();
@@ -94,7 +94,7 @@ export default {
       this.$refs.video.srcObject.getTracks().forEach(function(track) {
         track.stop();
       });
-      this.$refs.video.srcObject.srcObject = null;
+      this.$refs.video.srcObject = null;
     }
   },
   methods: {

src/features/OnlineExam/CheckComputer.vue

@@ -838,7 +838,7 @@ export default {
       this.$refs.video.srcObject.getTracks().forEach(function(track) {
         track.stop();
       });
-      this.$refs.video.srcObject.srcObject = null;
+      this.$refs.video.srcObject = null;
     }
     closeWsWithoutReconnect();
   },

src/features/OnlineExam/Examing/FaceMotion/FaceMotion.vue

@@ -1073,7 +1073,7 @@ export default {
         video.srcObject.getTracks().forEach(function(track) {
           track.stop();
         });
-        video.srcObject.srcObject = null;
+        video.srcObject = null;
       }
     },
   },