title: Gulp 4 Migration Errors (Did you forget to signal async completion?)
body: <p>I have a gulp 3 file which I am trying to upgrade to gulp 4. When I do so some of the tasks work others dont. The three errors that i am getting are as follows:</p>
  
  <p>clean-styles:</p>
  
  <pre><code>gulp.task('clean-styles', function (done) {
      var files = config.temp + '**/*.css';
      clean(files, done);
  });
  
  [23:47:05] The following tasks did not complete: clean-styles 
  [23:47:05] Did you forget to signal async completion?
  </code></pre>
  
  <p>scss-watcher: </p>
  
  <pre><code>gulp.task('scss-watcher', function () {
      gulp.watch([config.scss], ['styles']);
  });
  
  [23:51:27] 'scss-watcher' errored after 2.46 ms
  [23:51:27] Error: watching ./src/client/styles/styles.scss: watch task has to be a function (optionally generated by using gulp.parallel or gulp.series)
  </code></pre>
  
  <p>styles: (This will work if i remove the clean-styles series)</p>
  
  <pre><code>gulp.task('styles', gulp.series('clean-styles', function () {
  log('Compiling SCSS --&gt; CSS');
  
  return gulp
      .src(config.scss)
      .pipe($.scss())
      .pipe($.autoprefixer({ browsers: ['last 2 versions', '&gt; 5%'] }))
      .pipe(gulp.dest(config.temp));
  }));
  
  [23:52:42] The following tasks did not complete: styles, clean-styles
  [23:52:42] Did you forget to signal async completion?
  </code></pre>
  
  <p>vet: (Works)</p>
  
  <pre><code>gulp.task('vet', function () {
      log('Analyzing source with ESLint');
      return gulp
          .src(config.js)
          .pipe($.if(args.verbose, $.print()))
          .pipe($.eslint())
          .pipe($.eslint.format())
          .pipe($.eslint.failOnError());
  });
  </code></pre>
  
  <p>functions:</p>
  
  <pre><code>function clean(path, done) {
      log('Cleaning: ' + $.util.colors.blue(path));
      del(path, done);
  }
  
  function log(msg) {
      if (typeof(msg) === 'object') {
          for (var item in msg) {
              if (msg.hasOwnProperty(item)) {
                  $.util.log($.util.colors.blue(msg[item]));
              }
          }
      }
      else {
          $.util.log($.util.colors.blue(msg));
      }
  }
  </code></pre>
  
  <p>I have to be missing something. Can anyone fill me in on what I am missing?</p>