fix: forward error reason to fetch controller

lib/fetch/index.js

@@ -180,14 +180,15 @@ async function fetch (input, init = {}) {
       // 1. Set locallyAborted to true.
       locallyAborted = true
 
-      // 2. Abort the fetch() call with p, request, responseObject,
+      // 2. Assert: controller is non-null.
+      assert(controller != null)
+
+      // 3. Abort controller with requestObject’s signal’s abort reason.
+      controller.abort(requestObject.signal.reason)
+
+      // 4. Abort the fetch() call with p, request, responseObject,
       //    and requestObject’s signal’s abort reason.
       abortFetch(p, request, responseObject, requestObject.signal.reason)
-
-      // 3. If controller is not null, then abort controller.
-      if (controller != null) {
-        controller.abort()
-      }
     },
     { once: true }
   )

test/fetch/issue-2171.js

@@ -0,0 +1,25 @@
+'use strict'
+
+const { fetch } = require('../..')
+const { DOMException } = require('../../lib/fetch/constants')
+const { once } = require('events')
+const { createServer } = require('http')
+const { test } = require('tap')
+
+test('error reason is forwarded - issue #2171', { skip: !AbortSignal.timeout }, async (t) => {
+  const server = createServer(() => {}).listen(0)
+
+  t.teardown(server.close.bind(server))
+  await once(server, 'listening')
+
+  const timeout = AbortSignal.timeout(100)
+  await t.rejects(
+    fetch(`http://localhost:${server.address().port}`, {
+      signal: timeout
+    }),
+    {
+      name: 'TimeoutError',
+      code: DOMException.TIMEOUT_ERR
+    }
+  )
+})