mir-kiosk-snap-launch is deprecated and the `wayland-launch` script you ship is racy
You pick up wayland-launch from a deprecated project:
https://github.com/MirServer/mir-kiosk-snap-launch
We are fixing that source, so that you can simply rebuild, but the project has been deprecated in favour of:
https://github.com/MirServer/iot-example-graphical-snap
The specific problem is that the script can hit a race condition: