Assets without protocol was inserted in header with a single slash

[f-liva]

Since version 3.0.0, links without protocol in the pages are placed in the link header with only one slash instead of two.

E.g.

<link rel="stylesheet" href="//cdn.jsdelivr.net/npm/tingle.js@0.15.1/dist/tingle.min.css">

Was appended to request headers with a single leading slash

...
links: </cdn.jsdelivr.net/npm/tingle.js@0.15.1/dist/tingle.min.css>; rel=preload; as=style,...

Instead of with two leading slashes (as until version 2.0.6)

...
links: <//cdn.jsdelivr.net/npm/tingle.js@0.15.1/dist/tingle.min.css>; rel=preload; as=style,...

In doing so, the asset is considered relative to the site's url rather than absolute as an external resource.

You can see a live demo of the problem here, by opening the development console.

https://staging2.vivi.city/it

[f-liva]

Maybe I think the problem is located on the regex used to detects urls

If we edit the regex like that it should work: https://regex101.com/r/JlFWRN/1