null missing in generated typescript for sibling properties of recursive schemas when only one option provided in "oneOf"

[DustyLamp]

Describe the bug
Generated Typescript for properties that refer to a schema where sibling properties are recursive are missing null in union when only a single option is included in "oneOf" .

Minimal reproduction

{
    "openapi": "3.0.0",
    "info": {
        "title": "The API",
        "contact": {
            "email": "[email protected]"
        },
        "version": "1.0.0"
    },
    "paths": {
        "/api/hello": {
            "get": {
                "summary": "Hello",
                "operationId": "sayHello",
                "requestBody": {
                    "content": {
                        "application/json": {
                            "schema": {
                                "$ref": "#/components/schemas/Foo"
                            }
                        }
                    }
                }
            }
        }
    },
    "components": {
        "schemas": {
            "Bar": {
                "type": "object",
                "properties": {
                    "name": {
                        "type": "string"
                    }
                }
            },
            "Foo": {
                "type": "object",
                "properties": {
                    "bar": {
                        "oneOf": [
                            {
                                "$ref": "#/components/schemas/Bar"
                            }
                        ],
                        "nullable": true
                    },
                    "foos": {
                        "type": "array",
                        "items": {
                            "$ref": "#/components/schemas/Foo"
                        }
                    }
                }
            }
        }
    }
}

Expected behavior
What was generated:

...
export type Foo = Partial<{
    bar: Bar;
    foos: Array<Foo>;
}>;
...

What is expected:

...
export type Foo = Partial<{
    bar: Bar | null;
    foos: Array<Foo>;
}>;
...