Optional array / tuple elements

I have defined a tuple type with an optional element like this:

type tuple23 = [ number, string, string | undefined ];

The translation I get is:

{
    "$schema": "http://json-schema.org/draft-06/schema#",
    "additionalItems": {
        "anyOf": [
            {
                "type": "number"
            },
            {
                "type": "string"
            },
            {
                "type": "string"
            }
        ]
    },
    "items": [
        {
            "type": "number"
        },
        {
            "type": "string"
        },
        {
            "type": "string"
        }
    ],
    "minItems": 3,
    "type": "array"
}

The problem is that the undefined has been lost: minItems should be 2. What I expect is:

{
    "$schema": "http://json-schema.org/draft-06/schema#",
    "items": [
        {
            "type": "number"
        },
        {
            "type": "string"
        },
        {
            "type": "string"
        }
    ],
    "minItems": 2,
    "maxItems": 3,
    "type": "array"
}

[auroranil]

Same thing happens for me: When using type Array<SomeInterface | null>, typescript-json-schema ignores the null type in the “items” property.

[ali-habibzadeh]

Same issue here. Undefined is missing. something?: number | undefined; in an array becomes

{"type":"object","properties":{"something":{"type":"number"}

and undefined just goes puff!