JTD compileSerializer and compileParser failure with optionalProperties

[jkav77]

What version of Ajv are you using? Does the issue happen if you use the latest version?
8.11.2: the latest version

Ajv options object
{}

Your code

import Ajv, { JTDSchemaType } from "ajv/dist/jtd";
const ajv = new Ajv();

interface TestObject {
  first?: string;
  second?: string;
}

const testSchema: JTDSchemaType<TestObject> = {
  optionalProperties: {
    first: { type: "string" },
    second: { type: "string" },
  },
};

const serialize = ajv.compileSerializer(testSchema);
const parse = ajv.compileParser(testSchema);

const obj = { second: "test" };

const serializedObj = serialize(obj);
const parsedObj = parse(serializedObj);

console.log(serializedObj);
console.log(parsedObj);
console.log(parse.message, parse.position);

Output

{,"second":"test"}
undefined
unexpected token , 1

What results did you expect?
The serializer should create json code without the erroneous ,.

{"second":"test"}

Are you going to resolve the issue?
I will look into it, but I haven't found the source of the issue yet.

[jkav77]

Related to #2171, which addresses the additionalProperties instead of optionalProperties.