Having a little too much fun with typescript, ES6 Promises, and arrow functions

arrow.ts

class Person {
    private lifespan: number;
    private life: number;
    private YEAR_IN_SECONDS: number = 100;

    constructor(public name: string, public age: number) {
        this.lifespan = Math.floor(Math.random() * 40 + 60);
    }

    liveLife = () => {
        return new Promise<number>((resolve, reject) => {
            if (this.age <= this.lifespan) {
                this.life = setInterval(() => {
                    this.age++;
                    console.log(`${this.name} is now ${this.age} years old!`);
            
                    if (this.age > this.lifespan) {
                        console.log(`I regret to inform you that ${this.name} has died.`);
                        resolve(this.age);
                        clearInterval(this.life);
                    }
                }, this.YEAR_IN_SECONDS);
            } else {
                console.log('Reincarnation is not a thing in this program. ' + 
                    'Please make a new Person.');
                reject(this.age);
            }
        });
    }
}

let bob = new Person('Bob', 45);
let life = bob.liveLife()
    .then((age) => {
        console.log(`${bob.name} lived to the ripe old age of ${age}`);
        bob.liveLife()
            .catch(err => {});
    });

sample_output.txt

Bob is now 46 years old!
Bob is now 47 years old!
Bob is now 48 years old!
Bob is now 49 years old!
Bob is now 50 years old!
Bob is now 51 years old!
Bob is now 52 years old!
Bob is now 53 years old!
Bob is now 54 years old!
Bob is now 55 years old!
Bob is now 56 years old!
Bob is now 57 years old!
Bob is now 58 years old!
Bob is now 59 years old!
Bob is now 60 years old!
Bob is now 61 years old!
Bob is now 62 years old!
Bob is now 63 years old!
Bob is now 64 years old!
Bob is now 65 years old!
Bob is now 66 years old!
Bob is now 67 years old!
I regret to inform you that Bob has died.
Bob lived to the ripe old age of 67
Reincarnation is not a thing in this program. Please make a new Person.