Problem with .then in underscore.deferred?

bug_report.js

var Deferred = require( 'underscore.deferred' );

// using then won't throw any exceptions
var d1 = Deferred.Deferred();
d1.then( function( a ) {
  console.log( 'success', a );
  missing_var.destruction;
});
d1.resolve( 'test' );

// output:
// => success test

// using done/fail will
var d2 = Deferred.Deferred();
d2.done( function( a ) {
  console.log( 'success', a );
  missing_var.destruction;
});
d2.resolve( 'test' );

// output: 
// => success test
//   /tmp/deferred_bug/server.js:19
//    missing_var.destruction;
//    ^
//  ReferenceError: missing_var is not defined
//     at Object.<anonymous> (/private/tmp/deffered_Bug/wat.js:19:3)
//     at _d.Callbacks.fire (/private/tmp/deffered_Bug/node_modules/underscore.deferred/underscore.deferred.js:149:36)
//     at Object._d.Callbacks.self.fireWith (/private/tmp/deffered_Bug/node_modules/underscore.deferred/underscore.deferred.js:259:15)
//     at Object._d.Callbacks.self.fire [as resolve] (/private/tmp/deffered_Bug/node_modules/underscore.deferred/underscore.deferred.js:266:16)
//     at Object.<anonymous> (/private/tmp/deffered_Bug/wat.js:21:4)
//     at Module._compile (module.js:449:26)
//     at Object.Module._extensions..js (module.js:467:10)
//     at Module.load (module.js:356:32)
//     at Function.Module._load (module.js:312:12)
//     at Module.runMain (module.js:492:10)