Report errors that we can’t handle to users

[calebmer]

We want to report any errors that happen to users which we can’t handle. This keeps us honest and gives the user words for any weird things that happens in the app.

This means creating something an ExceptionReporter singleton and call that wherever we call console.error(). When replacing console.error()s with better exception reporting we should also do an audit of all points where there may be an error.