Optional fields are null

[boldt]

Imagine the following example:

var paperwork = require('paperwork');

var ScenarioSchemaPatch = {
    title: paperwork.optional(String),
    text: paperwork.optional(String)
};

var post = { text : "data", unknown_field : "foo"};

paperwork(ScenarioSchemaPatch, post, function (err, validated) {
  if (err) {
    console.error("Error",err);
  } else {
    console.log("JSON", validated);
  }
});

It returns:

JSON { title: null, text: 'data' }

Why is the title set to null, even if it was set to optional?