Fix: #4898 - requesting a non-existing surname breaks the individual …

…list

app/Module/IndividualListModule.php

@@ -23,6 +23,7 @@
 use Fisharebest\Webtrees\Auth;
 use Fisharebest\Webtrees\DB;
 use Fisharebest\Webtrees\Family;
+use Fisharebest\Webtrees\FlashMessages;
 use Fisharebest\Webtrees\I18N;
 use Fisharebest\Webtrees\Individual;
 use Fisharebest\Webtrees\Registry;
@@ -38,6 +39,7 @@
 use Psr\Http\Server\RequestHandlerInterface;
 
 use function array_filter;
+use function array_key_exists;
 use function array_keys;
 use function array_map;
 use function array_merge;
@@ -194,7 +196,6 @@ public function handle(ServerRequestInterface $request): ResponseInterface
                 ->redirectUrl($this->listUrl($tree, $params), StatusCodeInterface::STATUS_MOVED_PERMANENTLY);
         }
 
-
         // Make sure parameters are consistent with each other.
         if ($show_all_firstnames === 'yes') {
             $falpha = '';
@@ -214,6 +215,15 @@ public function handle(ServerRequestInterface $request): ResponseInterface
         $all_surnames     = $this->allSurnames($surname_data);
         $surname_initials = $this->surnameInitials($surname_data);
 
+        // We've requested a surname that doesn't currently exist.
+        if (!array_key_exists($surname, $all_surns)) {
+            $message = I18N::translate('There are no individuals with the surname “%s“', e($surname));
+            FlashMessages::addMessage($message);
+
+            return Registry::responseFactory()
+                ->redirectUrl($this->listUrl($tree));
+        }
+
         // Make sure selections are consistent.
         // i.e. can’t specify show_all and surname at the same time.
         if ($show_all === 'yes') {