SDL2 programs cause a failed assertion on Weston when program quits while pointer is confined

All SDL2 programs with a confined pointer cause this assert on the Weston code to fail when they quit:

https://gitlab.freedesktop.org/wayland/weston/-/blob/main/libweston/input.c#L4745

The problem is that, on SDL2 window closing, maybe_warp_confined_pointer() is called, and at that point confine_region is already NULL.

The consequence of this is that closing any SDL2 program with a confined pointer causes Weston to suddenly die, which isn't nice at all.

I have an small SDL2 test program here: https://github.com/vanfanel/LBE_DOCS/blob/master/SDL2-basic-example/ppp.c

...but all SDL2 programs with confined pointer are affected (Scummvm, etc).

I consider this is a Weston bug because it's only happening on this compositor, but of course I could be wrong.