quaint rune
It says out of bounds
#Movement
normal glen
You might want to add a text element to the upper left corner of your game which outputs the key variables in realtime. It will help you determine whether or not you are getting invalid values or if mouse updates are glitching out or lagging behind where your mouse cursor actually is.
IE: if its out of bounds, what mouse coordinates were captured? Are the mouse coordinates what you think they are? Is it being affected by the size of the window or its position in the OS? etc.