响应中的“ Access-Control-Allow-Credentials”标头为“”，必须为“ true”

在corsOptions中设置cors时，我添加了值凭据，它的工作原理如下：

private setCors(){        let whitelist = ['http://localhost:4200','http://localhost:80'];        let corsOptions = { origin: (origin:any, callback:any)=>{     if (whitelist.indexOf(origin) !== -1) {         callback(null, true)     } else {         callback(new Error('Not allowed by CORS'))     } },credentials: true        }        this.app.use(cors(corsOptions));    }