Inaccessible ErrorObject params in TypeScript

[vecerek]

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

Your typescript code

const validationError: ajv.ValidationError = new ajv.ValidationError([{
    dataPath: ".someKey",
    keyword: "enum",
    params: { allowedValues: ["1", "2", "3"] },
    schemaPath: "",
}]);
validationError.errors[0].params.allowedValues; // TypeError, see below

Typescript compiler error messages

$ tsc --target ES5 --noImplicitAny --noEmit spec/typescript/index.ts
spec/typescript/index.ts:60:34 - error TS2339: Property 'allowedValues' does not exist on type 'ErrorParameters'.
  Property 'allowedValues' does not exist on type 'RefParams'.

60 validationError.errors[0].params.allowedValues;

Describe the change that should be made to address the issue?
I opened a Draft PR here: #1318.

Are you going to resolve the issue?
I already did, needs review and a bit of help with validating the relationships between keywords and params.

[epoberezkin]

It's duplicate of #1090 - implemented in v7-beta