fix: use correct condition for available slots

src/Controller/Teamer/Application/CreateController.php

@@ -34,7 +34,7 @@ class CreateController extends AbstractController
 
         // Only allow applications on empty slots
         $availableSlots = (int) $assignment->getAvailableDispositions();
-        if (0 < $availableSlots) {
+        if (0 > $availableSlots) {
             $this->addFlash('error', 'Auf diesem Einsatz sind bereits alle Plätze belegt');
 
             return $this->redirectToRoute('app_teamer_index');