Error with snapcraft part including another part

[Alberto Mardegan]

Hi all!
   I've just added another part in the wiki, you can see it as the last 
one here:

     https://wiki.ubuntu.com/snapcraft/parts

It's the webapp-helper part. As you can see from its definition [1], 
it's meant to be built after the 'desktop-ubuntu-app-platform' part.

But when I run snapcraft on my project [2], all I get is an unhelpful 
red single line:
   'desktop-ubuntu-app-platform'
on the standard error (I reported this unhelpfulness as a bug).

Can you help me spot the error, or is it that snapcraft does not yet 
support having the "after" statement between remote parts?

Ciao,
   Alberto


[1]: 
https://gitlab.com/mardy/snapcraft-webapp-helper/blob/master/snapcraft.yaml
[2]: https://code.launchpad.net/~mardy/webapps-core/amazon-snap
[3]: https://bugs.launchpad.net/bugs/1652290