Response without schema

Is it possible to define a response that has no schema, e.g. for return an error?

Currently, the schema needs to be set, for example like

```js
responses: {
'415': {
description: 'Not supported',
schema: {}
}
}
```

which renders an empty json object in the schema on the documentation page.

Omitting the schema or setting it to null fails with

> Uncaught TypeError: Cannot read properties of undefined (reading 'generated')
at worker.js:268:20 in getType
at worker.js:265:126 in x
at worker.js:327:5 in j
at worker.js:442:20 in getParsedSchema
at worker.js:393:21
at worker.js:709:8

It would be nice if one could represent that nothing gets returned.