I have a JSON schema for a field:

  'age': { // age
      title: 'Your age',
      type: ['integer','null'],
      minimum: 1,
      maximum: 120
    }

And alpaca throws the error:
Uncaught Error: Alpaca caught an error with the default error handler: {"message":"Unable to find field class for type: undefined","reason":"FIELD_INSTANTIATION_ERROR"}

Is it possible to support multiple types for a field in Alpaca? I need to be able to support null in an integer field that is required. It's a required field, but null or an integer are valid values.