Recursive models cause RecursionError

[erpheus]

An API definition with recursive models causes a RecursionError when calling create_spec. The definition file does validate though (checked using openapi_spec_validator).

Here is a small working example:

openapi: "3.0.0"

info:
  title: "Test API"
  version: "1.0.0"

paths:
  /help:
    get:
      summary: "Gets general information about the service"
      responses:

        default:
          description: "Unexpected error"
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'

components:
  schemas:
    Error:
      type: object
      properties:
        message:
          type: string
        suberror:
          $ref: '#/components/schemas/Error'

yields the following

    self.openapi_spec = create_spec(yaml.load(open(openapi_path)))
  File "/opt/conda/lib/python3.6/site-packages/openapi_core/shortcuts.py", line 16, in create_spec
    return spec_factory.create(spec_dict, spec_url=spec_url)
  File "/opt/conda/lib/python3.6/site-packages/openapi_core/specs.py", line 88, in create
    components = self.components_factory.create(components_spec)
  File "/opt/conda/lib/python3.6/site-packages/openapi_core/components.py", line 37, in create
    schemas=list(schemas), responses=responses, parameters=parameters,
  File "/opt/conda/lib/python3.6/site-packages/openapi_core/schemas.py", line 245, in generate
    schema, _ = self.schemas_registry.get_or_create(schema_spec)
  File "/opt/conda/lib/python3.6/site-packages/openapi_core/schemas.py", line 232, in get_or_create
    return self.create(schema_deref), True
  File "/opt/conda/lib/python3.6/site-packages/openapi_core/schemas.py", line 207, in create
    deprecated=deprecated, all_of=all_of,
  File "/opt/conda/lib/python3.6/site-packages/openapi_core/schemas.py", line 43, in __init__
    self.properties = properties and dict(properties) or {}

...


  File "/opt/conda/lib/python3.6/site-packages/openapi_core/schemas.py", line 207, in create
    deprecated=deprecated, all_of=all_of,
  File "/opt/conda/lib/python3.6/site-packages/openapi_core/schemas.py", line 43, in __init__
    self.properties = properties and dict(properties) or {}
  File "/opt/conda/lib/python3.6/site-packages/openapi_core/schemas.py", line 164, in generate
    schema = self._create_schema(schema_spec)
  File "/opt/conda/lib/python3.6/site-packages/openapi_core/schemas.py", line 168, in _create_schema
    return SchemaFactory(self.dereferencer).create(schema_spec)
  File "/opt/conda/lib/python3.6/site-packages/openapi_core/schemas.py", line 207, in create
    deprecated=deprecated, all_of=all_of,
  File "/opt/conda/lib/python3.6/site-packages/openapi_core/schemas.py", line 41, in __init__
    self.type = schema_type and SchemaType(schema_type)
RecursionError: maximum recursion depth exceeded while calling a Python object