[6.x] Fix routing bug that causes missing parameters to be ignored (#…

…30659)

* Fix routing bug that causes missing parameters to be ignored

* Fix style

RouteUrlGenerator.php

@@ -200,7 +200,7 @@ protected function replaceRouteParameters($path, array &$parameters)
             // Reset only the numeric keys...
             $parameters = array_merge($parameters);
 
-            return (empty($parameters) && ! Str::endsWith($match[0], '?}'))
+            return (! isset($parameters[0]) && ! Str::endsWith($match[0], '?}'))
                         ? $match[0]
                         : Arr::pull($parameters, 0);
         }, $path);