Empty Schema Object in content response not detected

It resumes the ticket: https://github.com/Redocly/redoc/issues/2046

Describe the bug
Here it is an example:

post:
  responses:
    '422':
      description: Unprocessable Entity.
      content:
        'application/json':
          schema:

Expected behavior
It should return an error.

Swagger proposes should be object and stoplight studio proposes "schema" property type must be object.

Additional context

The correct empty fix for that should be:

post:
  responses:
    '422':
      description: Unprocessable Entity.
      content:
        'application/json': {}

It comes from: https://github.com/OAI/OpenAPI-Specification/blob/main/versions/3.0.3.md#operation-object-example

Ok visibly it is already implemented but I think there is some "miss".

With that example:

post:
  operationId: foobar
  tags:
    - Foo
  summary: Create a foo bar.
  description: Create a foo bar.
  responses:
    '201':
      description: Foo bar successful.
      content:
        'application/json': {}
    '403':
      description: Access Denied.
      content:
        'application/json':
          schema:
    '404':
      description: Not found
      content:
        'application/json':
          schema:

I've got only one error:

doc/api/foo/bar.yaml:
  16:11  error    spec  Expected type `Schema` (object) but got `null`

Start by reproducing the YAML example with the Redocly CLI and trace the OpenAPI response-content validation path; no source file or test is named in the issue. Done means a null schema value produces an error while an empty application/json object remains valid, with a regression test covering both cases.