better node.js stacktraces from event triggered code

nodejs-event-stacktrace.js

// the stack trace you really want that tells you how you originally got to the fs.readFile call
var stacktrace = new Error()
Error.captureStackTrace(stacktrace)

fs.readFile( path, encoding, function(err,data) {
  if( err ) {
    var stackerr = new Error('Unable to read file: '+path+' (error code: '+err.code+')')
    stackerr.errno = err.errno
    stackerr.code = err.code
    stackerr.path = err.path
    stackerr.stack = stacktrace.stack
    return callback(stackerr)
  }

  ...