Wrong typings for default responses

[gunzip]

On this input

openapi: 3.0.0
info:
  title: Pet API
  version: 1.0.0
paths:
  /pet/{petId}:
    get:
      summary: Get pet by ID
      parameters:
        - name: petId
          in: path
          required: true
          schema:
            type: string
      responses:
        "200":
          description: Success
          content:
            application/json:
              schema:
                type: object
                properties:
                  id:
                    type: string
                  name:
                    type: string
        "404":
          description: Pet not found
        default:
          description: Unexpected error

cli generates

export type GetPetPetIdResponses =
  FullResponse<GetPetPetIdResponseOK, 200>
  | FullResponse<GetPetPetIdResponseNotFound, 404>
  | FullResponse<GetPetPetIddefaultResponse, default>
  //                            // ^? typescript error

[toomuchdesign]

I confirm the issue. One possible solution could consist of extending FullResponse type to accept number | 'default', so that result type support type narrowing:

export interface FullResponse<T, U extends number | 'default'> {
  'statusCode': U;
  'headers': Record<string, string>;
  'body': T;
}

Of course this is just of of the possible approaches. Happy to support once we decide for a specific solution.