Fix undefined track_info data within "eledata_loaded" event

[Raruto]

Subject of the issue

Calling load() and on('eledata_loaded') sequentially does not ensure that all src/handlers files are downloaded at callback execution time, that is:

// waits until 'foo.gpx' is downloaded
controlElevation.on('eledata_loaded', ({track_info}) => console.log(track_info.distance)); // NB implicit dynamic import('src/handlers/distance.js')

// fetch 'foo.gpx'
controlElevation.load('foo.gpx'); 

Solution adopted

Refactor _loadLayer() function, in order to wait until this._modulesLoaded == true before triggering "eledata_loaded" event, that is:

const event_data = { data: geojson, layer: layer, name: this.track_info.name, track_info: this.track_info };

if (this._modulesLoaded) {
  this._fireEvt("eledata_loaded", event_data);
} else {
  this.once('modules_loaded', () => this._fireEvt("eledata_loaded", event_data));
}

Closes: #241

[Raruto]

@haldo98 let me know what you think about it

[haldo98]

I'll give it a try....

Thank U