fix: TypeError in Filters

TypeError: urldecode(): Argument #1 ($string) must be of type string, null given

Author: kenjis

system/Filters/Filters.php

@@ -376,6 +376,8 @@ private function setToolbarToLast(array $filters, bool $remove = false): array
      *
      * @param string|null $uri URI path relative to baseURL (all lowercase)
      *
+     * @TODO We don't need to accept null as $uri.
+     *
      * @return Filters
      */
     public function initialize(?string $uri = null)
@@ -385,7 +387,7 @@ public function initialize(?string $uri = null)
         }
 
         // Decode URL-encoded string
-        $uri = urldecode($uri);
+        $uri = urldecode($uri ?? '');
 
         $oldFilterOrder = config(Feature::class)->oldFilterOrder ?? false;
         if ($oldFilterOrder) {