fs.exists is the only function in all of node that has a callback that isn't in the errback form (a callback that takes an error as its first parameter). This wastes about 10 minutes of my time every time i forget about it. Please change this to be consistent with the rest of the node ecosystem.

fs.exists('/some/path', function(err, exists) {
   if(err) throw err
   if(exists) //do whatever
})