SocketError: other side closed

Upon connecting to a proxy with user:pass it’s all good, but when I try to make a request to an proxy which is IP authenticated, I get ‘SocketError: other side closed’. I’m not sending the proxy-authorization header as it’s not needed. Blanked the proxy ip and port below.

var Client = require('undici');
(async ()=>{
	const client = new Client("http://proxyip:proxyport")
	const response = await client.request({
	  method: 'GET',
	  path: 'https://api.ipify.org?format=json',
	  headers: {
	    //'proxy-authorization': `Basic ${Buffer.from(':').toString('base64')}`
	  }
	})

	response.body.setEncoding('utf8')
	let data = ''
	for await (const chunk of response.body) {
	  data += chunk
	}
	//
	console.log(response.statusCode)
	console.log(JSON.parse(data))

	client.close()
})();