In the trailhead module "Build an account locator app", in the 6th step, use events to add markers to the map step, I getting the following error: 

"This page has an error. You might just need to refresh it. Action failed: TrailApp57:AccountMap$controller$accountsLoaded [Invalid LatLng object: (undefined, undefined)] Failing descriptor: {TrailApp57:AccountMap$controller$accountsLoaded}"



As you can see that, the map and the accounts render on the page but the markers don't show up.

I have literally copied all the code on the trailhead page to avoid any typos and I am still getting this error. The only thing that's different is the leaflet package I have used is 1.4.0 instead of the 1.03 version suggested when the module was initially created. I went back and tried to download the 1.03 version but the older version has a size of 10mb, exceeding the 5mb static resource constraint. So now I am pretty stuck and I don't know what to do. 

For reference, here are my code for each of the controller and component: 

Account Map Component:

<aura:component>
    
    <aura:attribute name="map" type="Object"/>
    <aura:handler event="c:AccountsLoaded" action="{!c.accountsLoaded}"/>
    <ltng:require styles="/resource/leaflet/leaflet.css"
        scripts="/resource/leaflet/leaflet.js"
        afterScriptsLoaded="{!c.jsLoaded}" />
    <div id="map"></div>
</aura:component>

AccountMap Controller

({
    jsLoaded: function(component, event, helper) {
        var map = L.map('map', {zoomControl: false, tap: false}).setView([37.784173, -122.401557], 14);
        L.tileLayer('https://server.arcgisonline.com/ArcGIS/rest/services/World_Street_Map/MapServer/tile/{z}/{y}/{x}',
            {
                attribution: 'Tiles © Esri'
            }).addTo(map);
        component.set("v.map", map);
    },
    accountsLoaded: function(component, event, helper) {
        // Add markers
        var map = component.get('v.map');
        var accounts = event.getParam('accounts');
        for (var i=0; i<accounts.length; i++) {
            var account = accounts[i];
            var latLng = [account.Location__Latitude__s, account.Location__Longitude__s];
            L.marker(latLng, {account: account}).addTo(map);
        }  
    },
    accountSelected: function(component, event, helper) {
        // Center the map on the account selected in the list
        var map = component.get('v.map');
        var account = event.getParam("account");
        map.panTo([account.Location__Latitude__s, account.Location__Longitude__s]);
    }
})

Account Locator App Component:
 

<aura:component implements="force:appHostable,force:lightningQuickActionWithoutHeader,force:hasRecordId,force:appHostable,flexipage:availableForAllPageTypes">
	<aura:dependency resource="markup://force:navigateToSObject" type="EVENT"/>
    <div>
        <div>
            <c:AccountMap />
        </div>
        <div>
            <c:AccountList />
        </div>
    </div>
</aura:component>

Account List Component

<aura:component controller="AccountController">
    <aura:registerEvent name="accountsLoaded" type="c:AccountsLoaded"/>
    <aura:attribute name="accounts" type="Account[]"/> 
    <aura:handler name="init" value="{!this}" action="{!c.doInit}"/>
	<ul>
		<aura:iteration items="{!v.accounts}" var="account">
            <c:AccountListItem account="{!account}"/>
        </aura:iteration>    
    
    </ul>
	
</aura:component>

Account List Controller

({
    doInit : function(component, event) {
        var action = component.get("c.findAll");
        action.setCallback(this, function(a) {
            component.set("v.accounts", a.getReturnValue());
            window.setTimeout($A.getCallback(function() {
                var event = $A.get("e.TrailApp57:AccountsLoaded");
                event.setParams({"accounts": a.getReturnValue()});
                event.fire();
            }), 500);
        });
    $A.enqueueAction(action);
    }
})

There are additional components such as accountsloaded event and the accountsselected component but given the message, I think the issue is mostly related to account map component. 

Please help. 
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