Fix typedef
Fix typedef

Since `module.exports` is actually overwritten by the function returned by `create(Error)`, this is not an es6-module compatible scenario.
With this change,
```ts
import * as ono from 'ono'
throw ono(new Error('ono'))
```
and, perhaps more correctly
```ts
import ono = require('ono')
throw ono(new Error('ono'))
```
typecheck and generate correct code.

Before this change, only
```ts
import ono from 'ono'
throw ono(new Error('ono'))
```
and
```ts
import * as themodule from 'ono'
throw themodule.default(new Error('ono'))
```
would typecheck, both of which would throw at runtime by trying to call `ono.default()` or `ono.default.syntax()`, etc...
BigstickCarpet/ono,BigstickCarpet/ono,BigstickCarpet/ono