fix: gracefully handle when handling an error and socket is null

index.js

@@ -125,7 +125,9 @@ function finalhandler (req, res, options) {
     // cannot actually respond
     if (headersSent(res)) {
       debug('cannot %d after headers sent', status)
-      req.socket.destroy()
+      if (req.socket) {
+        req.socket.destroy()
+      }
       return
     }
 

test/test.js

@@ -571,4 +571,23 @@ describe('finalhandler(req, res)', function () {
         })
     })
   })
+
+  describe('req.socket', function () {
+    it('should not throw when socket is null', function (done) {
+      request(createServer(function (req, res, next) {
+        res.statusCode = 200;
+        res.end('ok')
+        process.nextTick(function () {
+          req.socket = null
+          next(new Error())
+        })
+      }))
+        .get('/')
+        .end(function () {
+          assert.strictEqual(this.res.statusCode, 200)
+          assert.strictEqual(this.res.text, 'ok')
+          done()
+        })
+    })
+  })
 })