TypeScript: Schema.issues() return type is incorrect

[garyposter]

Prerequisites

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

Mongoose version

5.11.0 through today

Node.js version

not pertinent

MongoDB server version

not pertinent

Typescript version (if applicable)

not pertinent

Description

Hi. The docs and code (see below) for schema.prototype.issues say that the result should be an array of [Index Definition, Index Options] pairs.

But the type definition shows that it returns an array of [IndexDefinition].

indexes(): Array<IndexDefinition>;

I think it should be indexes(): Array<[IndexDefinition, IndexOptions]>.

Code references:

• return getIndexes(this);
• indexes.push([field, options]);

Steps to Reproduce

Try writing the example plugin in Typescript.

function myPlugin(schema:Schema) {
  for (const index of schema.indexes()) {
    if (index[1].unique === undefined) {
      index[1].unique = true;
    }
  }
}

It will complain about numerous things. For example, "Property 'unique' does not exist on type 'IndexDirection'."
and "Property 'unique' does not exist on type '1'"

This makes Typescript happy.

  function myPlugin(schema:Schema) {
    const indexes = schema.indexes() as unknown as Array<[IndexDefinition, IndexOptions]>;
    for (const index of indexes) {
      if (index[1].unique === undefined) {
        index[1].unique = true;
      }
    }
  }

It would be nice if that were unnecessary.

Thank you!

Expected Behavior

The following does not generate complaints in TypeScript.

  function myPlugin(schema:Schema) {
    const indexes = schema.indexes();
    for (const index of indexes) {
      if (index[1].unique === undefined) {
        index[1].unique = true;
      }
    }
  }