Custom error for minLength on array property is not working

code sandbox:
https://codesandbox.io/s/friendly-boyd-c2qtm?file=/src/index.ts

The bellow schema returns the correct error message for minLength when it is defined on the parent or child prop, but it returns the default error when defined on an array property.

```typeScript
import Ajv from "ajv";
import ajvErrors from "ajv-errors";

export function validate(values: T, validationSchema: object) {
const ajv = new Ajv({ allErrors: true });

ajvErrors(ajv);

const validate = ajv.compile(validationSchema);

validate(values);

console.log(...validate.errors);
}

const SCHEMA = {
type: "object",
required: ["parent", "child", "arr"],
errorMessage: {
properties: {
parent: "parent custom length error ***111"
}
},
properties: {
parent: {
type: "string",
minLength: 5
},
arr: {
type: "array",
items: {
type: "object",
required: ["arrayProp"],
errorMessage: {
required:"custom required array prop",
properties: {
arrayProp: "arrayProp custom length error ***333 "
}
},
properties: {
arrayProp: {
type: "string",
minLength: 5
}
}
}
},
child: {
type: "object",
required: ["childProp"],
errorMessage: {
properties: {
childProp: "childProp custom length error ***222"
}
},
properties: {
childProp: {
type: "string",
minLength: 5
}
}
}
}
};

const DATA = {
parent: "aaaa",
child: {
childProp: "aaaa"
},
arr: [
{
arrayProp: "aaaa"
}
]
};

validate(DATA, SCHEMA);
```

these are the results:
```json
{instancePath: "/arr/0/arrayProp", schemaPath: "#/properties/arr/items/properties/arrayProp/minLength", keyword: "minLength", params: Object, message: "must NOT have fewer than 5 characters"}
{instancePath: "/child/childProp", schemaPath: "#/properties/child/errorMessage", keyword: "errorMessage", params: Object, message: "childProp custom length error ***222"}
{instancePath: "/parent", schemaPath: "#/errorMessage", keyword: "errorMessage", params: Object, message: "parent custom length error ***111"}
```