Warn when skipping installations
Warn when skipping installations

When we fail to parse an installation, emit some
warnings that give the user a chance to figure out
what is going wrong. I ran into the missing quotes
issue myself when I first tried to create a custom
installation.

Closes: #1939
Approved by: alexlarsson

flatpak/flatpak,matthiasclasen/flatpak,flatpak/flatpak,matthiasclasen/flatpak,flatpak/flatpak,matthiasclasen/flatpak,flatpak/flatpak,matthiasclasen/flatpak,matthiasclasen/flatpak,flatpak/flatpak