Server fails when favicon.ico is requested by a browser

[andrewbt]

We should probably make things more fault-tolerant

[timwis]

Yeah, I don't know why the browser is requesting favicon.ico on a json page -- normally it doesn't do that if the response Content-Type header is set to application/json. In fact, I thought I added that header to server.js and that fixed it. But it's definitely happening in the lambda function :/ at least it doesn't fail, it just shows an error in the network tab.

Are you just using server.js because it's easier to test? If so, we can definitely make it handle unknown routes pretty easily. I was also thinking of having server.js just delegate processing to handler.js (since handler.js is just a pure function) to have more parity.