To be fair, currently the test is a bit pointless (as it has no reason
to be a `SkinnableTestScene`, it gains precisely nothing from it - all
that is shown there is some generic components on song select). But that
is no worse then `master`, so look away for now.
These are tested framework-side to throw exceptions, but the
test is ignored for the source generated version because it quietly
allows this scenario.
The source gen project should eventually have an analyser for these
unsupported cases, or we could consider relaxing this particular case.