Panics ​

Panics abruptly stop program execution and "abort" it. If you're talking about an issue that will cause the program to crash while executing, using panic would be a good choice. The panic function is the builtin function. See the builtin documentations.

For example:

fn addToRef(rate: int, mut i: &int) {
    if i == nil {
        panic("i is nil reference")
    }
    i += rate
}

fn main() {
    addToRef(10, nil)
}

The code above is an example of panicking.