feat: reload the page with a flash when an htmx request fails

tests/Controller/BookingControllerTest.php

@@ -155,12 +155,6 @@ class BookingControllerTest extends WebTestCase
         self::assertNull($this->em->getRepository(Booking::class)->findOneBy(['resource' => $desk]));
     }
 
-    /**
-     * Note the status is 200, not 403: HtmxExceptionListener deliberately converts every
-     * exception on an htmx request -- access denied included -- into a visible error modal,
-     * because htmx discards a 4xx body and the click would otherwise do nothing at all.
-     * What matters here is that the booking survives.
-     */
     public function testReleasingAnotherPersonsBookingIsRefused(): void
     {
         $booking = new Booking($this->user('[email protected]'), $this->resource('D1'), new \DateTimeImmutable('2026-10-01'));
@@ -170,8 +164,7 @@ class BookingControllerTest extends WebTestCase
         $this->client->loginUser($this->user('[email protected]'));
         $this->client->request('POST', \sprintf('/bookings/%d/release', $booking->getId()), server: ['HTTP_HX-Request' => 'true']);
 
-        $response = $this->client->getResponse();
-        self::assertSame('body', $response->headers->get('HX-Retarget'));
+        self::assertResponseStatusCodeSame(Response::HTTP_FORBIDDEN);
         self::assertNotNull($this->em->getRepository(Booking::class)->find($booking->getId()));
     }