设置Composer源和下载PHP依赖包，完整包不需要执行这两条命令，git包是需要的

composer config -g repos.packagist composer https://mirrors.cloud.tencent.com/composer/
composer install

In Application.php line 449: Cannot access non-public property Composer\Downloader\TransportException::$code

版本也升级了。

You are already using the latest available Composer version 2.7.6 (stable channel).

请教会的朋友教一下。