Play sound in react-js

I try to play a sound on react-js but I can't make it start. I have my sound var initialised in my reactClass, before get InitialState:

var App = React.createClass({
audio: new Audio('files/audio.mp3'),
getInitialState: function () {
return {
  playSound: false,
   ........
 }
}

And this are the functions that I have for start and stop:

   playSound: function() {
if(!this.state.playSound){
    this.setState({
        playSound: true,
    }, function(){
      console.log("play sound 1");
      this.audio.play();
      console.log("play sound 2");
    });
}
},

stopSound: function() {
if(this.state.playSound){
    this.setState({
        playSound: false,
    }, function(){
        console.log("stop sound 1");
        this.audio.pause();
        console.log("stop sound 2");
    });
}
},

But I get back this answer:

react-app.js:346 Uncaught (in promise) DOMException: The element has no supported sources.

I have tried both with a .mp3 and .wav file. but it won't start. What am I doing wrong?

!!!! EDIT: Also tried adding a HTML item:

  <audio id="beep" loop>
         <source src="files/ring.wav" type="audio/wav" />
      </audio>

And with the following start/stop:

  playSound: function() {
if(!this.state.playSound){
    this.setState({
        playSound: true,
    }, function(){
      console.log("play sound 1");
      var audioElement = document.getElementById('beep');
      audioElement.setAttribute("preload", "auto");
      audioElement.autobuffer = true;
      audioElement.load();
      audioElement.play();
      console.log("play sound 2");
    });
}
},

stopSound: function() {
if(this.state.playSound){
    this.setState({
        playSound: false,
    }, function(){
        console.log("stop sound 1");
        var audioElement = document.getElementById('beep');
        audioElement.pause();
        console.log("stop sound 2");
    });
}
},

Then I get no error on start, but it doesn't start. When I press pause I get:

Uncaught (in promise) DOMException: The play() request was interrupted by a call to pause().

!!!! EDIT2:

Also I noticed, that if I set buttons, to play the sound. If I open the file manager, go to my index.html and open it, it works perfectly. If I try the page from the webpack-server: localhost:8000/app/index.html, it won't work. getting the same DOMException. why is this?

After trying for a while, I made 2 buttons, 1 to start the sound and one to stop, in my index.html file. So I tried that, and I noticed that it works from my file manager, but not if I try from the webpack server. So I checked my paths, and instead of: "files/audio.mp3" I changed it to "../files/audio.mp3". A rookie mistake, but that's what happens when you put a Android developer to work in javascript :)))