Code improvements

app/Providers/UploadFileProvider.php

@@ -25,7 +25,7 @@ class UploadFileProvider {
      * wo alle anderen Belege liegen.
      */
     public static function directoryFor(CostUnit $costUnit) : string {
-        return sprintf('%1$s/invoices/%2$s', app('tenant')->slug, $costUnit->id);
+        return sprintf('%1$s/invoices/%2$s', currentTenant()->slug, $costUnit->id);
     }
 
     public function saveUploadedFile() : ?InvoiceFile {