The website is showing JavaScript errors in the browser console when the page loads. This needs investigation and fixing. This appears to be related to the intentional bugs added for testing purposes.
When selecting ANY (at least in my case) of the dropdowns on the left the following javascript errors below occur and basically stop the editing of anything as the javascript required for the dropdown ...
The January 2018 update of Microsoft's Visual Studio Code editor incorporates the new TypeScript 2.7.1 edition, allowing for quicker fixing of errors in TypeScript and even regular JavaScript files.