Incorrect type for a `const` with an empty string value

[johnbillion]

Since #290 the const keyword is supported and acts as an alias for an enum with one value. This is great but it does not work correctly for a const that contains an empty string. Example:

Input:

"foo": {
	"const": ""
}

Expected output:

foo: ""

Actual output:

foo: {
	[k: string]: unknown;
};

An enum containing a single value of an empty string does work as expected:

"foo": {
	"enum": [
		""
	]
}

What use is a const with an empty string?

I use these for fields where the value is required and always a string but can be empty, for example an optional URL. Of course it should be nullable/optional really but this is a legacy application.

"url": {
	"oneOf": [
		{
			"type": "string",
			"format": "uri"
		},
		{
			"enum": [
				""
			]
		}
	]
},

[bcherny]

Published 10.1.5.