error_trap.bal

import ballerina/io;

public function main() {
    // If `foo()` does not panic, x will hold 
    // the value returned by `foo()`
    int|string|error x = foo(1);
    io:println(x);

    // If `foo()` panics, x will hold 
    // the error associated with the panic.
    x = trap foo(3);
    io:println(x);

    io:println("Done");
}

function foo(int i) returns int|string {
    match i {
        1 => {
            return 1;
        }
        2 => {
            return "two";
        }
        _ => {
            panic error("not one or two");
        }
    }
}