Laravel Mix multiple entry points generates one manifest.js

I currently have a problem trying to use multiple entry points in my Mix file.

// Mix frontend resources.
mix.js('resources/assets/js/app.js', 'public/js')
    .extract([
        'jquery', 'bootstrap', 'aos', 'lity',
    ]);

...

// Mix app resources.
mix.js('resources/assets/app/js/app.js', 'public/app/js');

I have three entry points in my Mix file. One for frontend, backend and my "public app" file. The code above stores my frontend vendor.js and manifest.js file inside public/app/js when it should be inside public/js.

When I then try to reference

<script src="{{ mix('js/manifest.js') }}"></script>
<script src="{{ mix('app/js/app.js') }}"></script>

it throws webpack errors:

Uncaught TypeError: Cannot read property 'call' of undefined
    at __webpack_require__ (manifest.js?id=09ecc9b…:55)
    at Object../node_modules/vue/dist/vue.common.js (app.js?id=6431fd7…:sourcemap:28709)
    at __webpack_require__ (manifest.js?id=09ecc9b…:55)
    at Object../resources/assets/app/js/app.js (app.js?id=6431fd7…:sourcemap:37900)
    at __webpack_require__ (manifest.js?id=09ecc9b…:55)
    at Object.0 (app.js?id=6431fd7…:sourcemap:38015)
    at __webpack_require__ (manifest.js?id=09ecc9b…:55)
    at webpackJsonpCallback (manifest.js?id=09ecc9b…:26)
    at app.js?id=6431fd7…:sourcemap:1

Is there currently a way to use multiple entry points in a Mix file?