fix: TypeScript-Fehler in batch route korrigiert

- Verwende lokale Variable curatorAssignments statt nullable assignments
- TypeScript erkennt jetzt korrekt, dass die Variable nicht null ist

app/api/songs/batch/route.ts

@@ -81,11 +81,12 @@ export async function POST(request: Request) {
 
         let assignments: { genreIds: Set<number>; specialIds: Set<number> } | null = null;
         if (context.role === 'curator') {
-            assignments = await getCuratorAssignments(context.curator.id);
+            const curatorAssignments = await getCuratorAssignments(context.curator.id);
+            assignments = curatorAssignments;
 
             // Validate genre/special toggles are within curator's assignments
             if (hasGenreToggle) {
-                const invalidGenre = genreToggleIds.some((id: number) => !assignments.genreIds.has(id));
+                const invalidGenre = genreToggleIds.some((id: number) => !curatorAssignments.genreIds.has(id));
                 if (invalidGenre) {
                     return NextResponse.json(
                         { error: 'Curators may only toggle their own genres' },
@@ -95,7 +96,7 @@ export async function POST(request: Request) {
             }
 
             if (hasSpecialToggle) {
-                const invalidSpecial = specialToggleIds.some((id: number) => !assignments.specialIds.has(id));
+                const invalidSpecial = specialToggleIds.some((id: number) => !curatorAssignments.specialIds.has(id));
                 if (invalidSpecial) {
                     return NextResponse.json(
                         { error: 'Curators may only toggle their own specials' },