vaapisink should move away from wl_shell
On a compositor like sway, vaapi segfaults according to the attached backtrace. To cite the explanation from IRC:
[emersion] ManDay: it seems gstreamer tries to use wl_shell, which is deprecated (and not supported by the compositor you're using)
[emersion] see wl_shell_get_shell_surface (wl_shell=0x0, surface=0x7fffd01881c0)