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I'm using Restify and somewhere in the Restify library, an exception is being thrown due to some bad inputs on the user side. I have some simplified code below that recreates the issue. The problem in the example below is in an asynchronous function that tries to execute doesntexist.nofunction. What happens is that an exception is thrown then caught in the "server.on('uncaughtException.." function, but the "err" object is actually an "IncomingMessage" type, not an "Error" type. I have a few questions about this.

1) Should exceptions thrown always be of type "Error" and if not, is this a bug in Restify?

2) Is it a best practice for libraries that take in a callback parameter to also set an "err" parameter if there's an error, and let the client handle it in the callback as opposed to the library throwing an exception?