`TypeError: can't convert undefined to object` error when `object` type has no `properties`

[DetachHead]

{
  "type": "object"
}

Uncaught (in promise) TypeError: can't convert undefined to object

it's valid to have no properties key on object types, for example when using additionalProperties:

{
  "type": "object",
  "additionalProperties": {
    "type": "string"
  }
}