(Bug) Type definitions: new signature for cursor.eachAsync() results in non-inferrable type arguments

[lincolnthree]

Do you want to request a feature or report a bug?
Bug.

What is the current behavior?

Upgraded: mongoose ^5.11.14 → ^5.12.3

After upgrading to 5.12.x, Compilation fails when using the Cursor.eachAsync() method with (previously) valid type arguments:

Property 'id' does not exist on type '(TournamentResultSchemaV1 & Document<any, {}>) | [TournamentResultSchemaV1 & Document<any, {}>]'.
  Property 'id' does not exist on type '[TournamentResultSchemaV1 & Document<any, {}>]'.ts(2339)

If the current behavior is a bug, please provide the steps to reproduce.

1. Call the cursor API and attempt to reference an instance as a non-array type.

What is the expected behavior?

The type should be narrowed based on the method signature used. If not using batch processing, the type should not be an Array type (or an optional array type).

What are the versions of Node.js, Mongoose and MongoDB you are using? Note that "latest" is not a version.

5.12.3

This was changed in #9902 afaik, and results in a breaking API change as compilation fails with what used to be proper usage of the eachAsync API.

[lincolnthree]

Thank you @vkarpov15!