fix select curriculumn error..

src/App.tsx

@@ -109,8 +109,14 @@ function App() {
           return next;
         });
       })
-      .catch(() => {
+      .catch((error) => {
-        if (!cancelled) setCourses([]);
+        if (cancelled) return;
+
+        setCourses([]);
+        setSelectedCourseId('');
+        window.localStorage.removeItem('lms-admin-selected-course-id');
+        setInitialCourseOpen(true);
+        setInitialCourseError(error instanceof Error ? error.message : '강좌 목록을 불러오지 못했습니다.');
       });
     return () => {
       cancelled = true;