quibble doesn't throw when file can't be found

- node v14.19.1
- fantasy directoy exists
- ./fantasy/fantasy.mjs doesn't exist

```
// index.mjs
import quibble from "quibble";

const run = async () => {
  await quibble.esm("./fantasy/fantasy.mjs");
};
run().catch(console.log).then(console.log);
```

when you run `node index.mjs` it just returns `undefined`. My expectation is that it should throw.



