I am getting below error.. seems html or java script issue with my script.

Challenge Not yet complete... here's what's wrong:
We can't find the right settings in the component boatsNearMe. Make sure the component was created according to the requirements, including the template tag that renders the spinner if isLoading is true.

Any thoughts ?

Hi Guys !! 

I am stuck at the challenge 7, trailhead showing error of a missing function, apparently it is present in my code !! Please help !
 

import { LightningElement, track, wire, api } from 'lwc';
import getBoatsByLocation from '@salesforce/apex/BoatDataService.getBoatsByLocation';
import { ShowToastEvent } from 'lightning/platformShowToastEvent';

const LABEL_YOU_ARE_HERE = 'You are here!';
const ICON_STANDARD_USER = 'standard:user';
const ERROR_TITLE = 'Error loading Boats Near Me';
const ERROR_VARIANT = 'error';
export default class BoatsNearMe extends LightningElement {
    @api boatTypeId;
    @track mapMarkers = [];
    @track isLoading = true;
    @track isRendered = false;
    latitude;
    longitude;
    @wire(getBoatsByLocation, { latitude: '$latitude', longitude: '$longitude', boatTypeId: '$boatTypeId' })
    wiredBoatsJSON({ error, data }) {
        if (data) {
            this.createMapMarkers(data);
        } else if (error) {
            this.dispatchEvent(
                new ShowToastEvent({
                    title: ERROR_TITLE,
                    message: error.body.message,
                    variant: ERROR_VARIANT
                })
            );
            this.isLoading = false;
        }
    }
    renderedCallback() {
        if (this.isRendered == false) {
            this.getLocationFromBrowser();
        }
        this.isRendered = true;
    }
    getLocationFromBrowser() {
        navigator.geolocation.getCurrentPosition(
            (position) => {
                this.latitude = position.coords.latitude;
                this.longitude = position.coords.longitude;
            },
            (e) => {

            }, {
            enableHighAccuracy: true
        }
        );
    }
    createMapMarkers(boatData) {
        this.mapMarkers = boatData.map(rowBoat => {
            return {
                location: {
                    Latitude: rowBoat.Geolocation_Latitude_s,
                    Longitude: rowBoat.Geolocation_Longitude_s
                },
                title: rowBoat.Name,
            };
        });
        this.mapMarkers.unshift({
            location: {
                Latitude: this.latitude,
                Longitude: this.longitude
            },
            title: LABEL_YOU_ARE_HERE,
            icon: ICON_STANDARD_USER
        });
        this.isLoading = false;
    }
}

Error :