feat: verbessere Fehlerbehandlung und optimiere das Laden von Vokabeln im VocabPracticeDialog

frontend/src/dialogues/socialnetwork/VocabPracticeDialog.vue

@@ -765,17 +765,18 @@ export default {
       }
       this.loading = true;
       try {
-        let res;
+        let res = null;
         let courseDueRes = null;
+
         // Wenn SRS-Modus auf Kurs-Ebene, lade kursweite fällige Items (Server liefert totalDueCount)
         if (this.srsMode && this.openParams.courseId && !this.openParams.lessonId) {
           try {
             courseDueRes = await apiClient.get(`/api/vocab/courses/${this.openParams.courseId}/srs/due`, { params: { limit: 100 } });
-            } catch (e) {
-              // ignore, fallback to lesson/chapters/vocabs endpoints
+          } catch (err) {
             courseDueRes = null;
           }
         }
+
         if (courseDueRes && Array.isArray(courseDueRes.data?.items) && courseDueRes.data.items.length > 0) {
           // Map server items to pool shape (use itemKey as id)
           this.pool = this.normalizePool((courseDueRes.data.items || []).map((it) => ({
@@ -786,12 +787,11 @@ export default {
           })));
           this.srsServerTotalDue = Number.isFinite(Number(courseDueRes.data?.totalDueCount)) ? Number(courseDueRes.data.totalDueCount) : null;
         } else {
+          // Fallback: lade Lehr- bzw. Kapitel-/Kurs-Vokabeln
           if (this.openParams.lessonId) {
             if (this.allVocabs && this.openParams.courseId) {
               res = await apiClient.get(`/api/vocab/courses/${this.openParams.courseId}/completed-lesson-vocabs`, {
-              params: {
-                untilLessonId: this.openParams.lessonId
-              }
+                params: { untilLessonId: this.openParams.lessonId }
               });
               this.pool = this.normalizePool(res.data?.vocabs || []);
             } else {
@@ -805,6 +805,7 @@ export default {
             res = await apiClient.get(`/api/vocab/chapters/${this.openParams.chapterId}/vocabs`);
             this.pool = this.normalizePool(res.data?.vocabs || []);
           }
+        }
       } catch (e) {
         console.error('Reload pool failed:', e);
         this.pool = [];