Instead of crashing, show the correct usage when running pan-x, pan-y or cursor-centric with script-message, or with script-binding but no argument.
Otherwise you can move your cursor outside the mpv window while having align-to-cursor "held" and make the script send illegal values
This script provides script bindings to pan videos and images, making mpv a better image viewer out of the box. Fixes #3038, fixes #15020.