Refactor native language loading in VocabCourseListView for improved clarity and error handling

- Renamed loadMyNativeLanguage to loadMyNativeLanguageId for better context.
- Enhanced error handling to log warnings when the languages list is empty or when the native language is not found.
- Improved debug logging to provide clearer insights into the native language loading process.

frontend/src/views/social/VocabCourseListView.vue

@@ -169,12 +169,12 @@ export default {
         this.languages = res.data?.languages || [];
         
         // Lade die Muttersprache des Benutzers
-        await this.loadMyNativeLanguage();
+        await this.loadMyNativeLanguageId();
       } catch (e) {
         console.error('Konnte Sprachen nicht laden:', e);
       }
     },
-    async loadMyNativeLanguage() {
+    async loadMyNativeLanguageId() {
       try {
         // Mappe UI-Sprache zu vocab_language Name
         const languageMap = {
@@ -190,9 +190,16 @@ export default {
         const nativeLanguageName = languageMap[uiLanguage] || 'Deutsch';
         
         // Finde die entsprechende vocab_language ID
+        if (this.languages && this.languages.length > 0) {
           const nativeLang = this.languages.find(lang => lang.name === nativeLanguageName);
           if (nativeLang) {
             this.myNativeLanguageId = nativeLang.id;
+            console.log(`[loadMyNativeLanguageId] Gefunden: ${nativeLanguageName} (ID: ${nativeLang.id})`);
+          } else {
+            console.warn(`[loadMyNativeLanguageId] Sprache "${nativeLanguageName}" nicht in languages-Liste gefunden. Verfügbare Sprachen:`, this.languages.map(l => l.name).join(', '));
+          }
+        } else {
+          console.warn(`[loadMyNativeLanguageId] languages-Liste ist leer.`);
         }
       } catch (e) {
         console.error('Konnte Muttersprache nicht laden:', e);