Wrong layouts generated for common doc types

Something strange is suddenly happening since today (2018-12-08). After a hot reload (10.2), in a demo when I navigate to the domain, or display a File or an audio, I an error displayed (see display-error.png).

Yesterday was ok, this morning too. So I can't navigate the domain or see the preview of a File for example.

Looking at what's inside the html, they (create/edit/view/etc.) have this:
```
<div class="container">
<div>This layout has not been configured yet.</div>
<div>Use <a href="https://connect.nuxeo.com/nuxeo/designer/#/cm-showcase-webui-nuxeo/layouts/document/Audio/create" target="_blank">Nuxeo Studio Designer</a> to generate it!</div>
</div>
```

This concerns only the default Document Types when they are re-declared in Studio. In my case: Domain, File, Audio, Picture and Video. (I redeclared them because I added custom schemas and facets).

Workaround: Explicitly create (click the "Configure" button) all the missing layouts.

So, as we would like to avoid having to do that for all of our demos, a fix would be greatly appreciated . Something like "When a layout for a default Nuxeo type is missing, use the default layout for this type"