xwayland: add error-checking to `server_start_lazy`
xwayland: add error-checking to `server_start_lazy`

This prevents a very unlikely crash in `xwayland_socket_connected`.

Refs #2163.

ascent12/wlroots,ascent12/wlroots,swaywm/wlroots,swaywm/wlroots,SirCmpwn/wlroots