WebGL App working in Chrome but not Firefox

Hi,
I have run across a wierd error on WebGL. I have compiled an app which works fine in Chrome, but in Firefox I get the error:

This code works fine on desktop and chrome.

Relevant code:

Code (CSharp):

1.  
2. // add this to it's module
3. Module.Get(node.Attributes["module"].Value).levels.Add(this);
4.  
5. // load image
6. string imagePath = Config.imagePath + node.Attributes["image"].Value;
7. TaskManager.SubmitTask(() => { return LoadImage(imagePath); });
8.  
9. // description of level
10. description = node.Attributes["description"].Value;

The game can be tested at dev.smartlabsltd.com.

 

Well which line exactly is the one with the null reference ?
Also, where are you loading the config from ?

 

It doesn't say.
The config is at dev.smartlabsltd.com/config.xml
It works on all other platforms.