Util for error branching?

People think they need separate channels for handling cancellations, but a simple error branching utility could be a better solution. Here's a trivial example:

```js
const handleErrors = (
fn,
onCancel = () => {}
) => e => {
(/Cancelled/.test(e.message)) ?
onCancel(e) : fn(e);
};

const handler = handleErrors(
e => console.log(`Not cancelled: ${ e }`),
c => console.log(`Cancelled: ${ c }`)
);
```

A `handleErrors()` utility could be fleshed out to handle custom error predicates, and to handle any number of different kinds of errors.