What is the right way to handle post request fail in NodeJS?

My previous question was really bad written (sorry for that!) so I'll try to do it right this time. I'm using NodeJS and I wrote the following code:

const car_reporter = {
    // Some Code here (Removed to make it clear)

    httpClient : null,

    scriptReport:  function(username, options) { // Some code here (Removed to make it clear)
    },

    APIReport: function(username, options) {
        if (!(this.httpClient)) {
            this.init();
        }
        try {
            if ('car' in options) {
                var reqConfig = {
                    method: 'post',
                    url: '/car',
                    headers: {
                        'content-type': 'application/json',
                    },
                    data: {
                        'carName': carName, // global
                        'username': username,
                        'car': options.car
                    }
                };
                this.httpClient(reqConfig).catch(function (error) {
                    throw new Error('Error while posting car\n' + error);
                });
            }
            // OTHER CODE HERE - NOTICE ME :) (Removed to make it clear)
        } catch (e) {
            return e;
        }
    },

    report: function (username, options) {
        if (username === null) {
            return new Error('Invalid username');
        }
        if (fs.existsSync(this.script_path)) {
            return this.scriptReport(username, options);
        } else {
            return this.APIReport(username, options);
        }
    },

    init: function() {
        this.httpClient = axios.create({
            baseURL: this.api_url
        });
    }
};

module.exports = car_reporter;

The way I call it:

function report_car(user_id, car) {
    var options = { car: car };
    var result = car_reporter.report(user_id, options);
    if (result instanceof Error) {
        logger.error(result);
    }
}

I want to throw Error in APIReport if the post failed. But it says: UnhandledPromiseRejectionWarning: Unhandled promise rejection. What is the right way here to handle errors and return Error if post request didn't work? I can't do return this.httpClient(... because there is other code after that request. I might need add .then(... but how do I know that the post failed?

from What is the right way to handle post request fail in NodeJS?