Copy-paste fix pattern
library CB-Math
fn main() {
u256 health = 20
u256 damage = 50
u256 safeHealth = CB-Math.max(health - CB-Math.min(health, damage), zero)
save safeHealth
}Why it happens
A checked unsigned operation produced a value below zero.
How to fix it
Compare before subtracting, clamp to zero, or use a signed type when negative values are intended.
Runtime and Studio now show this kind of page from the error dialog: plain message first, stable code second, original details third.