fix no data warning

src/features/OnlinePractice/OnlinePractice.vue

@@ -114,7 +114,7 @@ async function initData() {
   } else {
     examId = examList[0] && (examList[0].value as number);
   }
-  void getCourseList();
+  if (typeof examId === "number") void getCourseList();
 }
 
 onMounted(() => {