title: gulp 4.0 allowEmpty : true is not working for empty array
body: <pre><code>gulp.task(&quot;f1&quot;, () =&gt; {
      gulp.src([], {&quot;allowEmpty&quot;: true})
      .pipe(gulp.dest(location));
  })
  </code></pre>
  <p>Error: Invalid glob argument:  is thrown for the above snippet</p>
  <pre><code>gulp.task(&quot;f1&quot;, () =&gt; {
      gulp.src(&quot;[]&quot;, {&quot;allowEmpty&quot;: true})
      .pipe(gulp.dest(location));
  })
  </code></pre>
  <p>whereas, it is working fine. Is this the expected behaviour ? Anyway to use allowEmpty for empty array ?</p>
  <p>Anyhow the issue can be solved by skipping the task for empty array, just wondering is there any proper way to use allowEmpty for empty array.</p>
  <p>Any suggestion would be helpful. Thanks in advance</p>