fix: pass ProxyAgent proxy status code error

lib/fetch/index.js

@@ -1760,7 +1760,7 @@ async function httpNetworkFetch (
       fetchParams.controller.connection.destroy()
 
       // 2. Return the appropriate network error for fetchParams.
-      return makeAppropriateNetworkError(fetchParams)
+      return makeAppropriateNetworkError(fetchParams, err)
     }
 
     return makeNetworkError(err)

lib/fetch/response.js

@@ -426,15 +426,15 @@ function filterResponse (response, type) {
 }
 
 // https://fetch.spec.whatwg.org/#appropriate-network-error
-function makeAppropriateNetworkError (fetchParams) {
+function makeAppropriateNetworkError (fetchParams, err = null) {
   // 1. Assert: fetchParams is canceled.
   assert(isCancelled(fetchParams))
 
   // 2. Return an aborted network error if fetchParams is aborted;
   // otherwise return a network error.
   return isAborted(fetchParams)
-    ? makeNetworkError(new DOMException('The operation was aborted.', 'AbortError'))
-    : makeNetworkError('Request was cancelled.')
+    ? makeNetworkError(Object.assign(new DOMException('The operation was aborted.', 'AbortError'), { cause: err }))
+    : makeNetworkError(Object.assign(new DOMException('Request was cancelled.'), { cause: err }))
 }
 
 // https://whatpr.org/fetch/1392.html#initialize-a-response

test/proxy-agent.js

@@ -443,6 +443,30 @@ test('should throw when proxy does not return 200', async (t) => {
   t.end()
 })
 
+test('pass ProxyAgent proxy status code error when using fetch - #2161', async (t) => {
+  const server = await buildServer()
+  const proxy = await buildProxy()
+
+  const serverUrl = `http://localhost:${server.address().port}`
+  const proxyUrl = `http://localhost:${proxy.address().port}`
+
+  proxy.authenticate = function (req, fn) {
+    fn(null, false)
+  }
+
+  const proxyAgent = new ProxyAgent(proxyUrl)
+  try {
+    await fetch(serverUrl, { dispatcher: proxyAgent })
+  } catch (e) {
+    t.hasProp(e, 'cause')
+  }
+
+  server.close()
+  proxy.close()
+  proxyAgent.close()
+  t.end()
+})
+
 test('Proxy via HTTP to HTTPS endpoint', async (t) => {
   t.plan(4)