feat: improved error handling of xml parsers and loaders

src/Exception/TravelNotFoundException.php

@@ -0,0 +1,26 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Exception;
+
+use Symfony\Component\HttpKernel\Exception\HttpException;
+
+/**
+ * Exception thrown when attempting to load travel data that does not exist.
+ *
+ * This exception is used when a travel/date ID cannot be found in the
+ * available travel data sources (XML files or API).
+ */
+class TravelNotFoundException extends HttpException
+{
+    public function __construct(int $dateId, ?\Throwable $previous = null)
+    {
+        $message = sprintf(
+            'Travel data not found for date ID %d',
+            $dateId
+        );
+
+        parent::__construct(404, $message, $previous);
+    }
+}