fix further type problems

src/lib/helper/caseNumberOccupied.ts

@@ -1,13 +1,8 @@
 import { client } from '$lib/minio';
 
-/**
- * Check if caseNumber is used
- * @param {string} caseNumber
- * @returns {Promise<boolean}
- */
-export default async function caseNumberOccupied(caseNumber: string) {
+export default async function caseNumberOccupied (caseNumber: string): Promise<boolean> {
 	const prefix = `${caseNumber}/config.json`;
-	const promise = new Promise((resolve) => {
+	const promise: Promise<boolean> = new Promise((resolve) => {
 		const stream = client.listObjectsV2('tatort', prefix, false, '');
 		stream.on('data', () => {
 			stream.destroy();