-- schema.json --
{
    "$defs": {
        "enum": {
            "type": "string",
            "enum": [ "a", "b", "c" ]
        },
        "lists": {
            "description": "Single item or lists of various lengths.",
            "oneOf": [
                {
                    "type": "string",
                    "enum": [ "a", "b", "c" ]
                },
                {
                    "type": "array",
                    "oneOf": [
                        {
                            "items": [ { "const": "X" } ]
                        },
                        {
                            "items": [
                                { "const": "X" },
                                {
                                    "type": "string",
                                    "enum": [ "a", "b", "c" ]
                                }
                            ]
                        },
                        {
                            "items": [
                                { "const": "X" },
                                { "enum": [ "d", "e", "f" ] }
                            ]
                        }
                    ],
                    "additionalItems": false
                }
            ]
        }
    }
}
-- out/decode/extract --
ERROR:
from version https://json-schema.org/draft/2020-12/schema onwards, the value of "items" must be an object or a boolean:
    schema.json:18:29
from version https://json-schema.org/draft/2020-12/schema onwards, the value of "items" must be an object or a boolean:
    schema.json:21:29
from version https://json-schema.org/draft/2020-12/schema onwards, the value of "items" must be an object or a boolean:
    schema.json:30:29
