Fix intro guide

[rafJagCode]

Fixes intro guide error "invalid instaceof window.jquery"

Changes in client/vue.config.js

  const webpackPlugins = [
+    new webpack.ProvidePlugin({'window.jQuery': 'jquery'}),
    new webpack.DefinePlugin(envObject),
    new webpack.ContextReplacementPlugin(/moment[\\/]locale$/, /^\.\/(NOT_EXISTING)$/),
  ];

Error code: https://gist.github.com/rafJagCode/609d8773dc553cdfad9d4cb50ecc4124
Error img before fix and intro guide displayed after providing window.jquery:

---

UUID: 01148fda-c7f3-4668-a83d-e519eaf9407c

[CuriousMagpie]

@SabreCat Can you review this? Thanks!

[negue]

This is awesome! I've encountered this issue a couple of times but never found any clue how to fix that, and here you are with a fix 👏 👏 well done!!

@SabreCat LGTM and tested locally 🎉

[rafJagCode]

@negue Thanks, your comment made my day.
Taking this opportunity, I'll explain what happened here, as it might help in deciding whether my solution is the most appropriate. The problem is with the intro.js module. Despite the fact that it uses jQuery, it doesn't include it as a peerDependency and doesn't import jQuery in its files, it simply assumes that window.jQuery will be available on the page. Adding jQuery in webpack.ProvidePlugin results in webpack automatically importing jQuery in the modules that use it during the build.

[negue]

What I find weird is that this issue is only while in dev mode, on the production build this jquery issue never happens

I don't see any reason not to use your fix, one issue less to see while working in dev mode ^^

[rafJagCode]

@nague In production, this error also occurs, and the introduction is not showing. It's just that in production mode, runtime errors are not displayed on the screen, but you will see the same error in the console. This error, of course, disappears when you have unlocked all guide steps.

[CuriousMagpie]

I've tested this locally and the error in dev no longer occurs. @SabreCat, looks like it's ready for code review!