fixup: address review feedback

- Guard Readable.fromWeb against null body (204/304 responses)
- Add socket error handlers to CONNECT tunnel in proxy test
- Destroy socket in noproxy test's CONNECT handler so a regression
  fails fast instead of hanging

Author: MarshallOfSound

lib/download.js

@@ -28,7 +28,7 @@ async function download (gyp, url) {
 
   log.http(res.status, res.url)
 
-  const body = Readable.fromWeb(res.body)
+  const body = res.body ? Readable.fromWeb(res.body) : Readable.from([])
   return {
     status: res.status,
     url: res.url,

test/test-download.js

@@ -86,6 +86,8 @@ describe('download', function () {
         serverSocket.pipe(clientSocket)
         clientSocket.pipe(serverSocket)
       })
+      clientSocket.on('error', () => serverSocket.destroy())
+      serverSocket.on('error', () => clientSocket.destroy())
     })
 
     after(() => Promise.all([
@@ -118,7 +120,10 @@ describe('download', function () {
 
     let proxyUsed = false
     const pserver = http.createServer()
-    pserver.on('connect', () => { proxyUsed = true })
+    pserver.on('connect', (_, socket) => {
+      proxyUsed = true
+      socket.destroy()
+    })
 
     after(() => Promise.all([
       new Promise((resolve) => server.close(resolve)),