Mixtape doesn't cope well with the event stream connection droppnig

[PeterJCLaw]

I can't recall the details, however I believe there is a (somewhat known) issue whereby mixtape has issues if/when the connection to the srcomp-stream drops out. While the main cause of that in the past was memory issues in the CoffeeScript version of srcomp-stream (PeterJCLaw/srcomp-stream#5), those have been mitigated somewhat.

Given the impact that mixtape has when the stream does drop out, we should not assume that this is something which can be addressed purely on the server-side (as network issues or operational concerns might mean that the stream drops out anyway).

It would be great if someone with more information could expand on what the failure mode is, cc @WillB97 @prophile.

[PeterJCLaw]

@WillB97 you mentioned yesterday that the issue with the stream disconnecting was to do with an exponential backoff in the SSE library we're using. I'm not seeing that either in the sseclient code nor that behaviour in testing. Instead mixtape does seem to handle reconnecting ok, unless the stream is persistently gone -- then it just crashes.