Update method sig

src/Interface/BadgeableInterface.php

@@ -21,8 +21,8 @@ interface BadgeableInterface
     /**
      * Get the badge icon name
      *
-     * @return ?string Icon name
+     * @return ?string Icon name or `null` if no icon exists.
      */
-    public function getBadgeIcon(): string;
+    public function getBadgeIcon(): ?string;
 }