value, or handle the cases
when the promise rejects, is via the promise's <a href="https://api.emberjs.com/ember/3.1/classes/Promise/methods/then?anchor=then"><code>then()</code></a> method, which
accepts two optional callbacks, one for fulfillment and one for
rejection. If the promise fulfills, the fulfillment handler gets called
with the fulfilled value as its sole argument, and if the promise rejects,
the rejection handler gets called with a reason for the rejection as its
sole argument. For example:</p>