Type of sibling property of a ref property is unknown when validated via JTDSchemaType

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

8.11.2 (latest as of this writing)

**Ajv options object**

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

**JTD Schema**

```ts
type MyType = {
referenced: number;
stringProp: string;
};

const schema: JTDSchemaType = {
definitions: {
num: { type: "int32" }
},
properties: {
referenced: { ref: "num" },
stringProp: { type: "string" }
}
} as const;

```

**Sample data**

```ts
const data = {} as any;
```

**Your code**

```ts
const validate = ajv.compile(schema);

if (validate(data)) {
const revealType: never = data;
const stringProp: string = data.stringProp;
console.log(stringProp);
}
```

https://replit.com/@ento/IntrepidIndolentOutput#index.ts

^`strictNullChecks` is enabled in `tsconfig.json`

```json
"strictNullChecks": true,
```

**Validation result, data AFTER validation, error messages**

TypeScript's typecheck errors:

```
// const revealType
Type '{ referenced: number; stringProp: unknown; } & {}' is not assignable to type 'never'.

// const stringProp
Type 'unknown' is not assignable to type 'string'.
```

**What results did you expect?**

The type of `stringProp` to be `string` after being narrowed by `validate(data)`

**Are you going to resolve the issue?**

My current workaround is to hold the definition in a const and use it to compose the schema object. (The actual code is a bit more complex than this.)

```ts
const numSchema = { type: "int32" } as const;

const schema: JTDSchemaType = {
properties: {
referenced: numSchema,
stringProp: { type: "string" }
}
} as const;
```