don't freeze urlList for opaque filtered responses (#4656)

* don't freeze urlList for opaque filtered responses

* test

Author: KhafraDev

lib/web/fetch/response.js

@@ -453,7 +453,7 @@ function filterResponse (response, type) {
 
     return makeFilteredResponse(response, {
       type: 'opaque',
-      urlList: Object.freeze([]),
+      urlList: [],
       status: 0,
       statusText: '',
       body: null

test/fetch/issue-4647.js

@@ -0,0 +1,23 @@
+'use strict'
+
+const { createServer } = require('node:http')
+const { test } = require('node:test')
+const { fetch } = require('../..')
+
+// https://github.com/nodejs/undici/issues/4647
+test('fetch with mode: no-cors does not hang', async (t) => {
+  const a = createServer((req, res) => {
+    res.writeHead(200).end()
+  }).listen(0)
+
+  const b = createServer((req, res) => {
+    res.writeHead(301, { Location: `http://localhost:${a.address().port}${req.url}` }).end()
+  }).listen(0)
+
+  t.after(() => {
+    a.close()
+    b.close()
+  })
+
+  await fetch(`http://localhost:${b.address().port}/abc`, { mode: 'no-cors' })
+})