React-Leaflet marker files not found

Try to do this 🙂

React leaflet for some reason do not include images and you will need to reset
default icons image.

Below is some working example, I hope it will solve your issue.

You also can add icons from one of public link

https://cdnjs.com/libraries/Leaflet.awesome-markers

import React, { Component } from 'react';
import L from 'leaflet';
import {
    Map, TileLayer, Marker, Popup
} from 'react-leaflet'
import 'leaflet/dist/leaflet.css';
import './style.css';


import icon from 'leaflet/dist/images/marker-icon.png';
import iconShadow from 'leaflet/dist/images/marker-shadow.png';

let DefaultIcon = L.icon({
    iconUrl: icon,
    shadowUrl: iconShadow
});

L.Marker.prototype.options.icon = DefaultIcon;