Discriminated Unions

main.ts

interface MyError {
    type: "error";
    item: {status: number, msg: string};
}

interface MyNums {
    type: "mynums";
    item: number[];
}

interface MyNum {
    type: "mynum";
    item: number;
}

type Generic = MyError  | MyNum | MyNums

let test: Generic = {
    type: "error",
    item: {status: 10, msg: 'hello'}
}

let test1: Generic = {
    type: "mynum",
    item: 1
}