import { Icon } from "leaflet"
delete Icon.Default.prototype._getIconUrl
Icon.Default.mergeOptions({
iconRetinaUrl: require("leaflet/dist/images/marker-icon-2x.png"),
iconUrl: require("leaflet/dist/images/marker-icon.png"),
shadowUrl: require("leaflet/dist/images/marker-shadow.png")
})
The problem is described here.