What is the when.js equivalent of Q.js's "done()"?

What is the when.js equivalent of Q.js's "done()"?

In addition to then(), Q.js also has a done(). done() is usually called at
the end of a promise chain, like this:
promise .then(callback) .then(callback) .done(callback);
This will catch any rejections that were not handled by the previous
then()s, and it will handle any exceptions raised in then()'s callbacks.
Is there something similar in when.js? How do you handle exceptions raised
in callbacks? And what if you never register a rejection handler?