missing type property is improperly ignored without much warning

A Schema Object without a type key seems to just get dropped. The spec has little clarification for a case like this but I believe it is valid. This should either but clarified and made an error or the parser should handle this more gracefully recording that the attribute exists but for example has a default type (like object or something). It's also possible the warning should just be more specific.

example case.

swagger: '2.0'

info:
  title: example
  version: "0"

paths: {}

definitions:
  aDef:
    type: object
    properties:
      initialValue:
        description: "I'm invisible!"

cross post of
https://github.com/swagger-api/swagger-codegen/issues/5335
related:
https://github.com/swagger-api/swagger-codegen/issues/5164

Start with the Swagger 2.0 example in the issue and trace how the parser handles the Schema Object under definitions.aDef.properties.initialValue when type is absent. Review the linked swagger-codegen issues 5335 and 5164 for context and determine whether the expected result is an error, a warning, or preserving the attribute with a default type.