rework vehicle handling

backend/src/services/member.service.ts

@@ -236,6 +236,8 @@ class MemberService {
       // Attach rank history when the profile exists
       if (member.profile) {
         member.dienstgrad_verlauf = await this.getDienstgradVerlauf(userId);
+      } else {
+        member.dienstgrad_verlauf = [];
       }
 
       return member;
@@ -583,7 +585,15 @@ class MemberService {
         FROM mitglieder_profile
       `);
 
-      return result.rows[0] as MemberStats;
+      return (result.rows[0] as MemberStats) ?? {
+        total: 0,
+        aktiv: 0,
+        passiv: 0,
+        ehrenmitglied: 0,
+        jugendfeuerwehr: 0,
+        'anwärter': 0,
+        ausgetreten: 0,
+      };
     } catch (error) {
       logger.error('Error fetching member stats', { error });
       throw new Error('Failed to fetch member stats');