Improve XKCD command

[groowyCZ]

Code tested only separately from the bot in NPM runkit. Further testing recommended.

Code tested in NPM runkit:

require('request')
const request = require("request-promise")

class TestVehicle {

    constructor() {
        this.XKCD_BASE_URL = "https://xkcd.com/";
        this.XKCD_API_SUFFIX = "/info.0.json";
    }

    async apiRequest(location) {
        return await request({
            uri: this.XKCD_BASE_URL + location,
            json: true,
            headers: {
                'User-Agent': 'WilsonBot',
            },
        });
    }

    parseComic(xkcdResponseJSON) {
        let comic = {};
        comic.id = xkcdResponseJSON.num;
        comic.title = xkcdResponseJSON.safe_title;
        comic.description = xkcdResponseJSON.alt;
        comic.image = xkcdResponseJSON.img;
        comic.url = this.XKCD_BASE_URL + xkcdResponseJSON.num;

        return comic;
    }

    async fetchLatestComic() {
        let responseJSON = await this.apiRequest(this.XKCD_API_SUFFIX);
        return this.parseComic(responseJSON);
    }

    async fetchComicByID(id) {
        let responseJSON;

        try {
            responseJSON = await this.apiRequest(id + this.XKCD_API_SUFFIX);
        } catch(e) {
            return {error: "Couldn't find that ID."};
        }

        return this.parseComic(responseJSON);
    }

    async fetchRandomComic(id) {
        let latestComic = await this.fetchLatestComic();
        let randomComicID = 1 + Math.floor(Math.random() * latestComic.id);
        return await this.fetchComicByID(randomComicID);
    }

    fetchComic(arg) {
        if (arg === "latest") {
            return this.fetchLatestComic();
        } else if (arg) {
            return this.fetchComicByID(arg);
        } else {
            return this.fetchRandomComic();
        }
    }
}

let tv = new TestVehicle()
tv.fetchComic("latest").then(x => {
    if (x.error) {
        console.log(x.error);
    } else {
        console.log(x);
    }
}).catch(e => console.error(e));

[enteryournamehere]

Perfect, thank you!