[Types] Typing for Schema.discriminator does not include options parameter

[JstnMcBrd]

Prerequisites

• I have written a descriptive issue title
• I have searched existing issues to ensure the bug has not already been reported

Mongoose version

8.10.0

Node.js version

22.12.0

MongoDB server version

6.13.0

Typescript version (if applicable)

5.7.3

Description

The types for Schema.discriminator only allow 2 parameters (name and schema):

// https://github.com/Automattic/mongoose/blob/master/types/index.d.ts#L300
discriminator<DisSchema = Schema>(name: string | number, schema: DisSchema): this;

But in the actual code, it is clear that the function accepts an additional parameter (options):

// https://github.com/Automattic/mongoose/blob/master/lib/schema.js#L639
Schema.prototype.discriminator = function(name, schema, options) {
  this._applyDiscriminators = this._applyDiscriminators || new Map();
  this._applyDiscriminators.set(name, { schema, options });

  return this;
};

This discrepancy in the types makes it so users cannot specify different name and value without typecasting:

const schema = new Schema({});
(schema as any).discriminator("Name", new Schema({}), "value");

(Which incidentally, is the best workaround for #7422)

Steps to Reproduce

Try to create a discriminator on a Schema with a different name and value.

const schema = new Schema({});
schema.discriminator("Name", new Schema({}), "value"); // Type error

Expected Behavior

Types should reflect actual code.

const schema = new Schema({});
schema.discriminator("Name", new Schema({}), "value"); // No type error

[vkarpov15]

Fix is in #15249. Worth mentioning that it looks like Schema.prototype.discriminator() only supports DiscriminatorOptions as 3rd param, so schema.discriminator("Name", new Schema({}), "value") won't work, but schema.discriminator("Name", new Schema({}), { value: "value" }) will