Ошибка в gulp. Как пофиксить?

Во время первого запуска выскакивает такая ошибка, запускается localhost, но файл расширения sass не редактируется:

Running 'default'...
[13:37:29] Using gulpfile ~\Desktop\Initial Project\_optimized_gulp_sass\gulpfile.js
[13:37:29] Starting 'styles'...
[13:37:29] Finished 'styles' after 14 ms
[13:37:29] Starting 'express'...
[13:37:29] Finished 'express' after 78 ms
[13:37:29] Starting 'livereload'...
[13:37:29] Finished 'livereload' after 59 ms
[13:37:29] Starting 'watch'...
[13:37:29] Finished 'watch' after 14 ms
[13:37:29] Starting 'default'...
[13:37:29] Finished 'default' after 33 μs
Error in plugin 'sass'
Message:
    sass\header.sass
Error: Invalid CSS after "body {}": expected 1 selector or at-rule, was "font-size: 16px;"
        on line 5 of sass/header.sass
>> body {}
   -------^

При повторном запуске уже не работает localhost:

Running 'default'...
[13:39:01] Using gulpfile ~\Desktop\Initial Project\_optimized_gulp_sass\gulpfile.js
[13:39:01] Starting 'styles'...
[13:39:01] Finished 'styles' after 13 ms
[13:39:01] Starting 'express'...
[13:39:01] Finished 'express' after 78 ms
[13:39:01] Starting 'livereload'...
[13:39:01] Finished 'livereload' after 56 ms
[13:39:01] Starting 'watch'...
[13:39:01] Finished 'watch' after 14 ms
[13:39:01] Starting 'default'...
[13:39:01] Finished 'default' after 36 μs

... Uhoh. Got error listen EADDRINUSE :::35729 ...
Error: listen EADDRINUSE :::35729
    at Object.exports._errnoException (util.js:1050:11)
    at exports._exceptionWithHostPort (util.js:1073:20)
    at Server.setupListenHandle [as _listen2] (net.js:1259:14)
    at listenInCluster (net.js:1307:12)
    at Server.listen (net.js:1406:7)
    at Server.listen (C:\Users\Александр\Desktop\Initial Project\_optimized_gulp_sass\node_modules\tiny-lr\lib\server.js:162:15)
    at Gulp.<anonymous> (C:\Users\Александр\Desktop\Initial Project\_optimized_gulp_sass\gulpfile.js:20:9)
    at module.exports (C:\Users\Александр\Desktop\Initial Project\_optimized_gulp_sass\node_modules\orchestrator\lib\runTask.js:34:7)
    at Gulp.Orchestrator._runTask (C:\Users\Александр\Desktop\Initial Project\_optimized_gulp_sass\node_modules\orchestrator\index.js:273:3)
    at Gulp.Orchestrator._runStep (C:\Users\Александр\Desktop\Initial Project\_optimized_gulp_sass\node_modules\orchestrator\index.js:214:10)

You already have a server listening on 35729
You should stop it and try again.

events.js:163
      throw er; // Unhandled 'error' event
      ^

Error: listen EADDRINUSE 127.0.0.1:80
    at Object.exports._errnoException (util.js:1050:11)
    at exports._exceptionWithHostPort (util.js:1073:20)
    at Server.setupListenHandle [as _listen2] (net.js:1259:14)
    at listenInCluster (net.js:1307:12)
    at doListen (net.js:1432:7)
    at GetAddrInfoReqWrap.asyncCallback [as callback] (dns.js:62:16)
    at GetAddrInfoReqWrap.onlookup [as oncomplete] (dns.js:78:10)

Помогите пожалуйста. Как пофиксить данную проблему?