I'm not 100% sure why this fix works, but it does, and I'm still
fulfilling my obligations to free resources, so I'm rolling with it.

See the added comment for some more details.  Basically there seems to
be a problem with destroying the SDL renderer before destroying the
window, though that would appear to be the correct order of operations.
I'm not sure if I'm doing something wonky to cause the issue, but simply
rearranging the order of destruction makes the crash go away, so here we
are.