Bug#974888: growlight: Reproducibly segfaults on pressing F1

[Nick Black]

I've found one problem that would lead to a SIGABRT on shutdown,
which might or might not include a message about an assertion
failure. This was an issue in the underlying Notcurses library,
which will be fixed in 2.0.9 and 2.1.0. I think there's at least
one other kind of failure on shutdown, though.