using "_opt.defaultMeta" in TypeScript

[b4h0-c4t]

What version of Ajv are you using? Does the issue happen if you use the latest version?
v6.12.3

Your typescript code

import metaSchema from 'ajv/lib/refs/json-schema-draft-04.json';

// create Ajv instance(ajv) and more code...
ajv._opts.defaultMeta = metaSchema.id;
...

Typescript compiler error messages

Property '_opts' does not exist on type 'Ajv'.

Describe the change that should be made to address the issue?
Add type definition for "_opt".
Please tell me If there are other solutions.

Are you going to resolve the issue?
I'll do this if a fix is ​​needed.

[b4h0-c4t]

Proposed a simple solution.
I hope you can see this PR.

[b4h0-c4t]

@epoberezkin
There's another problem with PR that solves this problem.
The purpose of the PR is to "access _opts.defaultMeta" but this solution doesn't do that.

Can I have another chance to fix this?