title: Gulp: Getting dest.on error when adding suffix to file name. Any ideas on how to fix?
body: <p>I want to use Gulp to minify some .css files, rename theme to .min.css and move them to another directory.</p>
  <p>For that I have set up the following (as per many tutorials I find online):</p>
  <pre><code>const cleanCSS = require('gulp-clean-css');
  const rename = require('rename');
  
  gulp.task('mincss', () =&gt; {
    return gulp.src('css/*.css')
      .pipe(cleanCSS({compatibility: 'ie8'}))
      .pipe(rename({
        suffix: '.min'
      }))
      .pipe(gulp.dest('css/minified'));
  });
  </code></pre>
  <p>However, this produces the error:</p>
  <blockquote>
  <p>TypeError: dest.on is not a function</p>
  </blockquote>
  <p>I've Googled this but do not understand it.</p>
  <p>It works fine if I remove rename pipe.</p>
  <p>Would anyone know how to fix this?</p>
  <p>(My Gulp version is  4.0.2)</p>