Cannot use typescript validation with const fields in schema

What version of Ajv are you using? Does the issue happen if you use the latest version? 8.11.0, yes in case it’s relevant, I’m using typescript 4.5.2

Your code

import Ajv, {JSONSchemaType} from "ajv"
const ajv = new Ajv()

interface Foo {
  constantValue: 'FOO'
}

const schema: JSONSchemaType<Foo> = {
  type: 'object',
  properties: {
    constantValue: {
      const: 'FOO'
    }
  }
}

This will cause a typescript compilation error:

Type '{ type: "object"; properties: { name: { const: "FOO"; }; }; }' is not assignable to type 'UncheckedJSONSchemaType<Foo, false>'.
  The types of 'properties.name' are incompatible between these types.
    Type '{ const: "FOO"; }' is not assignable to type '{ $ref: string; } | (UncheckedJSONSchemaType<"FOO", false> & { const?: "FOO" | undefined; enum?: readonly "FOO"[] | undefined; default?: "FOO" | undefined; })'.
      Type '{ const: "FOO"; }' is not assignable to type '{ type: "string"; } & StringKeywords & { allOf?: readonly UncheckedPartialSchema<"FOO">[] | undefined; anyOf?: readonly UncheckedPartialSchema<"FOO">[] | undefined; ... 4 more ...; not?: UncheckedPartialSchema<...> | undefined; } & { ...; } & { ...; }'.
        Property 'type' is missing in type '{ const: "FOO"; }' but required in type '{ type: "string"; }'.

What results did you expect? Typescript would compile without issues.

[Unga]

constantValue: { type: 'string', const: 'FOO' }

[theahura]

That did it. Thanks so much!