<FIX> 메서드 체이닝 적용

Author: goldm0ng

src/main/java/roomescape/reservation/presentation/ReservationController.java

@@ -32,10 +32,8 @@ public ResponseEntity<Reservation> createReservation(@Valid @RequestBody Reserva
 
     @DeleteMapping("/reservations/{reservationId}")
     public ResponseEntity<Void> deleteReservation(@PathVariable Long reservationId) {
-        Optional<Reservation> deleteReservation = reservationService.deleteReservation(reservationId);
-        if (deleteReservation.isEmpty()) {
-            throw new NotFoundReservationException();
-        }
+        Reservation deletedReservation = reservationService.deleteReservation(reservationId)
+                .orElseThrow(NotFoundReservationException::new);
 
         return ResponseEntity.noContent().build();
     }