Error gulp build

gistfile1.txt

C:\Users\darwin\Source\Repos\naut\angularjs> gulp build
[13:56:04] Using gulpfile ~\Source\Repos\naut\angularjs\gulpfile.js
[13:56:04] Starting 'build'...
[13:56:04] Starting 'clean-scripts'...
[13:56:04] *** Cleaning: app/js/*{js,map}
[13:56:04] Starting 'clean-styles'...
[13:56:04] *** Cleaning: app/css/*{css,map}
[13:56:04] Starting 'clean-markup'...
[13:56:04] *** Cleaning: index.html,app/views/
[13:56:04] Finished 'clean-scripts' after 20 ms
[13:56:04] Finished 'clean-styles' after 14 ms
[13:56:04] Finished 'clean-markup' after 15 ms
[13:56:04] Starting 'clean'...
[13:56:04] Finished 'clean' after 7.27 μs
[13:56:04] Starting 'production'...
[13:56:04] Finished 'production' after 4.28 μs
[13:56:04] Starting 'bootstrap'...
[13:56:04] *** Compiling Bootstrap..
[13:56:04] Starting 'styles'...
[13:56:04] *** Compiling styles from LESS to CSS..
[13:56:04] Starting 'clean-scripts'...
[13:56:04] *** Cleaning: app/js/*{js,map}
[13:56:04] Starting 'views'...
[13:56:04] *** Compiling HTML...
[13:56:05] Finished 'clean-scripts' after 433 ms
[13:56:05] Starting 'templatecache'...
[13:56:05] *** Compiling HTML...
[13:56:05] *** Creating AngularJS templateCache..
[13:56:08] Finished 'bootstrap' after 4.25 s
[13:56:09] Finished 'templatecache' after 3.91 s
[13:56:09] Starting 'index'...
[13:56:09] *** Compiling HTML...

C:\Users\darwin\Source\Repos\naut\angularjs\node_modules\gulp-html-prettify\node_modules\event-stream\node_modules\map-stream\index.js:103
        throw err
              ^
Error: Path C:\Users\darwin\Source\Repos\naut\angularjs\app\css\styles.css not found!
    at getFiles (C:\Users\darwin\Source\Repos\naut\angularjs\node_modules\gulp-usemin\lib\blocksBuilder.js:58:15)
    at module.exports (C:\Users\darwin\Source\Repos\naut\angularjs\node_modules\gulp-usemin\lib\blocksBuilder.js:96:20)
    at Transform._transform (C:\Users\darwin\Source\Repos\naut\angularjs\node_modules\gulp-usemin\index.js:16:22)
    at Transform._read (C:\Users\darwin\Source\Repos\naut\angularjs\node_modules\gulp-usemin\node_modules\through2\node_modules\readable-stream\lib\_stream_transform.js:184:10)
    at Transform._write (C:\Users\darwin\Source\Repos\naut\angularjs\node_modules\gulp-usemin\node_modules\through2\node_modules\readable-stream\lib\_stream_transform.js:172:12)
    at doWrite (C:\Users\darwin\Source\Repos\naut\angularjs\node_modules\gulp-usemin\node_modules\through2\node_modules\readable-stream\lib\_stream_writable.js:237:10)
    at writeOrBuffer (C:\Users\darwin\Source\Repos\naut\angularjs\node_modules\gulp-usemin\node_modules\through2\node_modules\readable-stream\lib\_stream_writable.js:227:5)
    at Transform.Writable.write (C:\Users\darwin\Source\Repos\naut\angularjs\node_modules\gulp-usemin\node_modules\through2\node_modules\readable-stream\lib\_stream_writable.js:194:11)
    at Stream.ondata (stream.js:51:26)
    at Stream.emit (events.js:107:17)
PS C:\Users\darwin\Source\Repos\naut\angularjs>