default_env is not properly encapsulated.

[cfurst]

Let's say you have lib a that usues envious as well as your own script that uses envious:
lib A has the following config file:

var envious = require('envious');
envious.qa = {
"places" : { "oneplace":"/one/path",
                 "anotherplace": "/another/path"}
}
envious.dev={
  "places":{"oneplace":"/one/path"}
}
envious.default_env="dev"
var config = envious.apply()
module.exports = config

now in your config you have the following:

var envious = require('envious');
envious.qa = {
"places" : { "one":"1",
                 "two": "10"}
}
envious.dev={
  "places":{"one" : "1"}
}
// no default declared here!
var config = envious.apply();
modules.export = config;

The configuration in your script INHERITS the default_env decalration in the library and will now inherit, unintentionally, all the undeclared keys of envious.dev.places, no matter what you set NODE_ENV to. Which of course will cause unexpected behavior in your code.

You have to set default_env to a "falsy" value to cancel it out. However in envious.js there is no warning, nor error thrown if there is a declaration of that default env.