Copy-paste fix pattern
fn main() {
array names = ["Ada", "Grace"]
u256 at = 1
if (at < len(names)) {
println(names[at])
} else {
println("No item at that index")
}
}Why it happens
The program tried to read or write an array slot that does not exist.
How to fix it
Check len(array), clamp the index to 0..len(array)-1, or create the missing item before assignment.
Runtime and Studio now show this kind of page from the error dialog: plain message first, stable code second, original details third.