Gulp error: The following tasks did not complete: Did you forget to signal async completion?

I have the following gulpfile.js, which I’m executing via the command line gulp message:

var gulp = require('gulp');

gulp.task('message', function() {
  console.log("HTTP Server Started");
});

I’m getting the following error message:

[14:14:41] Using gulpfile ~\Documents\node\first\gulpfile.js
[14:14:41] Starting 'message'...
HTTP Server Started
[14:14:41] The following tasks did not complete: message
[14:14:41] Did you forget to signal async completion?

I’m using gulp 4 on a Windows 10 system. Here is the output from gulp --version:

[14:15:15] CLI version 0.4.0
[14:15:15] Local version 4.0.0-alpha.2