Gistlyn hosted gists don't work

[edwin-jones]

If you visit http://gistlyn.com in firefox 55 or chrome 61 (on Windows) and try to use the example gist you always get a script id error or the compile never finishes.

If you inspect the session you can see the heartbeat fails:

post to http://gistlyn.com/event-heartbeat?/{id} response 404 Subscription '{id}' does not exist