If you've been experiencing an error lately trying to load the viewer, this should now be resolved. We were finally able to track down a scenario where we could reproduce the issue, and once we had that it was resolved quickly. It was only affecting some people, and most were not hit by it, and it was only on the WebGL build (as the title states).
If for any reason the latest version still throws an error, ensure you've got the latest version with the fix by clearing cache. Instructions:
http://igpmanager.com/forum-thread/7158
The error would have looked something like this:
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