What properties does Node.js express’s Error object expose?

The Error object is actually a native object provided by V8, rather than by node.js or express.

The property that will most likely be of the most use to you is stack. E.g.,

console.log(new Error('NotFound').stack);

There are other properties available as well, such as name and message. You can read up on them here. Just be aware that those docs are for Mozilla’s JavaScript engine, so don’t count on anything flagged as Non-standard to work in node.js.