Laravel5.5 エラーページファイルセット
resources/views/errors/layouts/base.blade.php
resources/views/errors/400.blade.php
resources/views/errors/401.blade.php
resources/views/errors/403.blade.php
resources/views/errors/404.blade.php
resources/views/errors/500.blade.php
resources/views/errors/503.blade.php