fix: mail preview endpoint not loading and crashing on null data

Register web.php in bootstrap/app.php (was missing, so the route was
never loaded). Add null checks for all model queries with helpful error
messages instead of TypeErrors.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

api/routes/web.php

@@ -5,23 +5,49 @@ use App\Mail\RegistrationApprovedMail;
 use App\Mail\RegistrationConfirmationMail;
 use App\Mail\RegistrationRejectedMail;
 use App\Models\Event;
-use App\Models\Organisation;
 use App\Models\Person;
 use App\Models\UserInvitation;
 use Illuminate\Support\Facades\Route;
 
 if (app()->environment('local', 'staging')) {
     Route::get('/mail-preview/{type}', function (string $type) {
-        $org = Organisation::first();
+        $supportedTypes = [
+            'registration-confirmation',
+            'registration-approved',
+            'registration-rejected',
+            'invitation',
+        ];
+
+        if (! in_array($type, $supportedTypes)) {
+            abort(404, "Unknown mail type '{$type}'. Supported types: " . implode(', ', $supportedTypes));
+        }
+
+        if ($type === 'invitation') {
+            $invitation = UserInvitation::first();
+
+            if (! $invitation) {
+                return response('No UserInvitation found in the database. Create one first to preview this mail.', 422);
+            }
+
+            return new InvitationMail($invitation);
+        }
+
         $event = Event::first();
         $person = Person::first();
 
+        if (! $event || ! $person) {
+            $missing = collect([
+                'Event' => $event,
+                'Person' => $person,
+            ])->filter(fn ($v) => $v === null)->keys()->implode(', ');
+
+            return response("No test data found. Missing: {$missing}. Seed the database first.", 422);
+        }
+
         return match ($type) {
             'registration-confirmation' => new RegistrationConfirmationMail($person, $event),
             'registration-approved' => new RegistrationApprovedMail($person, $event),
             'registration-rejected' => new RegistrationRejectedMail($person, $event, 'Helaas geen plek meer.'),
-            'invitation' => new InvitationMail(UserInvitation::first()),
-            default => abort(404),
         };
     });
 }