Battery can go to the minus value - this is not really an issue per se, but next time, you can use if (battery <= 0){battery = 0} which will make sure it never goes below zero.
-I used that code. But it didn't work because it works after the character dies. I haven't been able to check this well.
I will try to fix the stuck bug and the infinitely falling bug when it becomes.
Thanks for commenting :)
( I used google translator, so it may not be accurate. )
[ Edit ]
Fixed a bug that caused getting stuck on walls or floors, level selection errors, battery draining below 0% bug.
and installed a transparent barrier to prevent falling to infinity.
Updates will be made after the evaluation period ends. thank you.