Node server crashes if it can't connect to HMIS server

[cecilia-donnelly]

If the Node JS server (for this client application) fails to connect to the HMIS server named in local.js then it will crash with error:

events.js:141
      throw er; // Unhandled 'error' event
      ^

Error: connect ECONNREFUSED 127.0.0.1:8080
    at Object.exports._errnoException (util.js:870:11)
    at exports._exceptionWithHostPort (util.js:893:20)
    at TCPConnectWrap.afterConnect [as oncomplete] (net.js:1063:14)

This specific error was generated with a local instance of HMIS (localhost:8080), but I've seen this happen with a remote server, too.

We should return an error to the user instead of crashing the client server.

[kfogel]

I recall that @slifty mentioned this to me as a known unhandled error, way back when. So it's not unexpected -- demo-only code and all that. Still, we should fix it, now that the client is getting more use.