'map_join' fails when map arg is dict: 'map_id' aesthetic is required to show data on map

[alshan]

UK = {
    'lon': [-2.598046, -2.378320, -2.466210, -3.169335, -1.938867, 
            -0.576562, -0.312890, 0.873632, 0.082617, -2.598046], 
    'lat': [51.030349, 51.797754, 53.945750, 54.561879, 55.193929, 
            53.816229, 52.924809, 52.525588, 51.113188, 51.030349]
}
Germany = {
    'lon': [7.685156, 9.926367, 13.661718, 14.101171, 11.464453, 
            12.870703, 8.564062, 8.651953, 6.806250, 6.938085, 7.685156], 
    'lat': [53.294124, 54.049078, 53.608160, 51.305902, 50.221916, 
            48.679365, 48.007575, 49.485266, 50.024691, 51.552493, 53.294124]
}
France = {
    'lon': [-2.246484, 2.367773, 7.245703, 5.268164, 6.586523, 
            2.895117, 2.279882, -0.532617, -0.356835, -2.246484], 
    'lat': [48.095702, 50.586036, 48.795295, 46.365136, 44.169607, 
            43.663114, 43.088157, 43.631315, 46.516550, 48.095702]
}
polygons = dict(
    lon = UK['lon'] + Germany['lon'] + France['lon'],
    lat = UK['lat'] + Germany['lat'] + France['lat'],
    country = ['UK' for _ in UK['lon']] + ['Germany' for _ in Germany['lon']] + ['France' for _ in France['lon']]
)

population = dict(
    Country = ["UK", "Germany", "France"],
    Population = [66.65e6, 83.02e6, 66.99e6]
)

ggplot() + geom_polygon(aes(fill='Population'), data=population, map=polygons, map_join=['Country','country'], alpha=0.3)

The same issue occurs when using livemap like:

ggplot() + geom_livemap() + geom_polygon(aes(fill='Population'), data=population, map=polygons, map_join=['Country','country'], alpha=0.3)

And another thing: this error message ('map_id' aesthetic is required to show data on map) is obsolete - we have switched to map_join parameter - please update the error message.