Error with discriminator

I'm trying to create an OpenAPI specification with a body with a discriminator field and two models, using oneOf. However, when I try to put the discriminator field itself in each of the models, to get that in the documentation as well, the UI throws an error "😱 Could not render rt, see the console.". In the console, I get an opaque "TypeError: e.$$ref is undefined" error message.

Reproducible example:

openapi: 3.0.2
info:
  title: FastAPI
  version: 0.1.0
paths:
  /test:
    post:
      summary: Test Post
      operationId: test_post_test_post
      requestBody:
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/Body'
        required: true
      responses:
        '200':
          description: Successful Response
          content:
            application/json:
              schema: {}
components:
  schemas:
    Body:
      title: Body
      required:
        - either
      type: object
      properties:
        either:
          title: Either
          oneOf:
            - $ref: '#/components/schemas/ModelA'
            - $ref: '#/components/schemas/ModelB'
          discriminator:
            propertyName: q_type
            mapping:
              A: '#/components/schemas/ModelA'
              B: '#/components/schemas/ModelB'
    ModelA:
      title: ModelA
      required:
        - q_type
        - x
      type: object
      properties:
        q_type:
          title: Q Type
          enum:
            - A
          type: string
        x:
          title: X
          type: integer
    ModelB:
      title: ModelB
      required:
        - q_type
        - 'y'
      type: object
      properties:
        q_type:
          title: Q Type
          enum:
            - B
          type: string
          'y':
            title: 'Y'
            type: string