Typescript usage - from pain to gain

example-1.ts

export type User = {
    name: string,
    age: number,
    roles: Role[];
}

export function isValidUser(user: unknown): user is User {
    return  !!(user as User).name && 
            !!(user as User).age && 
            !!(user as User).roles && 
            Array.isArray((user as User).roles);
}