Vue pages renders as blank

[Jorrit Steetskamp]

When I make a new Vue project and use wkhtmltopdf, it renders a blank page.

Steps to reproduce:

1. vue create hello-world
   
2. Choose: Default (Vue 3, babel, eslint)
3. npm run serve
4. Check in browser that it works: http://localhost:8081
5. ./wkhtmltopdf --javascript-delay 10000 --debug-javascript "http://localhost:8081/" "test.pdf"
   

The response is:

Loading pages (1/6)
Warning: undefined:0 TypeError: 'undefined' is not a function
Counting pages (2/6)
Resolving links (4/6)
Loading headers and footers (5/6)
Printing pages (6/6)
Done

The PDF is rendered, but the page is blank. I assume 10 seconds is more than enough to render it after load.

This is just a case to illustrate my problem. My real project is more complex, because I use webpack, axios and more. While I get one warning in the example above,  I get multiple warnings during processing of wkhtmltopdf in my real project:

Loading pages (1/6)
Warning: http://localhost:8080/build/runtime.js:1 SyntaxError: Parse error
Warning: http://localhost:8080/build/vendors-node_modules_core-js_internals_set-species_js-node_modules_core-js_modules_es_array_f-0880e9.js:7 SyntaxError: Parse error
Warning: http://localhost:8080/build/vendors-node_modules_axios_index_js-node_modules_core-js_modules_es_array_reverse_js-node_mod-330420.js:7 SyntaxError: Parse error
Warning: http://localhost:8080/build/src_Resources_js_templateLoader_js.js:8 SyntaxError: Parse error
Warning: http://localhost:8080/build/app_pdf.js:8 SyntaxError: Parse error
Counting pages (2/6)
Resolving links (4/6)
Loading headers and footers (5/6)
Printing pages (6/6)
Done

In my real project, the URL works fine in the browser, just like the hello-world project above. I also tried it with option --window-status and/or with a JavaScript setTimeout, but none seems to do the trick.

What should I do different to make wkhtmltopdf work with Vue? Thanks for any help.