public function writeConfig($values = [], $overwrite = false)
    {
        if (!$overwrite) {
            $values = $values + (array) $this->getConfig();
        }

        $path = $this->getPath().'/theme.yaml';
        if (!File::exists($path)) {
            throw new ApplicationException('Path does not exist: '.$path);
        }

        $contents = Yaml::render($values);
        File::put($path, $contents);
        $this->configCache = $values;
    }