[Bug]: Nullable Generic Scalar generated as object

[maennchen]

Describe the bug

When using a scalar as a generic, the OpenAPI output sometimes is defined as type object even though the file is not an object.

Using typespec v0.62.0

Reproduction

Typespec

scalar ISODate extends string;

alias RangeUnbound = null;

model Range<Inner> {
  from: Inner | RangeUnbound;
  to: Inner | RangeUnbound;
  lowerInclusive: boolean;
  upperInclusive: boolean;
}

model ISODateRange is Range<ISODate> {}

OpenAPI Output

ISODateRange:
  type: object
  required:
    - from
    - to
    - lowerInclusive
    - upperInclusive
  properties:
    from:
      type: object
      allOf:
        - $ref: '#/components/schemas/ISODate'
      nullable: true
    to:
      type: object
      allOf:
        - $ref: '#/components/schemas/ISODate'
      nullable: true
    lowerInclusive:
      type: boolean
    upperInclusive:
      type: boolean

Expected

RangeUnbound:
  type: null
ISODateRange:
  type: object
  required:
    - from
    - to
    - lowerInclusive
    - upperInclusive
  properties:
    from:
      oneOf:
        - $ref: '#/components/schemas/ISODate'
        - $ref: '#/components/schemas/RangeUnbound'
    to:
      oneOf:
        - $ref: '#/components/schemas/ISODate'
        - $ref: '#/components/schemas/RangeUnbound'
    lowerInclusive:
      type: boolean
    upperInclusive:
      type: boolean

or

ISODateRange:
  type: object
  required:
    - from
    - to
    - lowerInclusive
    - upperInclusive
  properties:
    from:
      type: string
      nullable: true
    to:
      type: string
      nullable: true
    lowerInclusive:
      type: boolean
    upperInclusive:
      type: boolean

Checklist

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