protected function missing(string $resource, Theme $theme = null)
    {
        $path = $this->getBasePath();

        $message = "{$resource} not found in {$path}";

        if (!$this->themeIsDefault($theme)) {
            $default = $this->getBasePath($this->getDefaultTheme());

            $message .= " or {$default}";
        }

        $this->logger->warning($message);
    }