fix: refuse implausible accommodation booking prices

src/Exception/ImplausibleBookingPriceException.php

@@ -0,0 +1,40 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Exception;
+
+use App\Entity\Groups\AccommodationBooking;
+
+/**
+ * Thrown when a computed accommodation booking total is too large to be a real price.
+ *
+ * The total is a product of pax count, nights and catalog prices, so a single mistyped figure
+ * anywhere in that chain can produce a number nobody could owe. Storing it is pointless — it
+ * would go out on an offer — and a signed INT column answers it with SQLSTATE 22003, which says
+ * nothing about where the mistake is. Failing here instead names the price and the inputs it
+ * came from.
+ */
+class ImplausibleBookingPriceException extends \RuntimeException
+{
+    /**
+     * What the backoffice is told. The total itself is in the log; the actionable part is the
+     * house's price rows, which is where the stray digit is.
+     */
+    public const string FORM_ERROR_MESSAGE = 'Der berechnete Gesamtpreis ist unplausibel hoch. Bitte die Preise und Leistungen des Gruppenhauses prüfen.';
+
+    public function __construct(int $totalPrice, int $paxCount, int $nights, ?\Throwable $previous = null)
+    {
+        parent::__construct(
+            sprintf(
+                'Refusing to store an implausible booking total of %d (ceiling %d, in minor units) for %d people over %d nights — check the catalog prices for this house.',
+                $totalPrice,
+                AccommodationBooking::MAX_TOTAL_PRICE,
+                $paxCount,
+                $nights,
+            ),
+            0,
+            $previous,
+        );
+    }
+}