types: handle compiling with exactOptionalPropertyTypes

[vkarpov15]

Fix #16273

Summary

Fix compiling with TypeScript's exactOptionalPropertyTypes flag. I also added a separate test folder with a separate tsconfig.json for testing compiling with that flag set.

Examples

[Copilot]

Pull request overview

Updates Mongoose’s published TypeScript declaration files to compile cleanly when consumers enable exactOptionalPropertyTypes (and skipLibCheck: false), and adds a dedicated type-test setup to continuously validate that configuration.

Changes:

• Fix TS2344 errors under exactOptionalPropertyTypes by excluding undefined from Options['enum'] when threading enum options through recursive path-type resolution.
• Add a new test/types/exactOptionalPropertyTypes folder with its own tsconfig.json that enables exactOptionalPropertyTypes + skipLibCheck: false.
• Expand tstyche’s test glob to include nested test/types/** type tests.

Reviewed changes

Copilot reviewed 3 out of 6 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
types/inferschematype.d.ts	Removes undefined from Options['enum'] in recursive ResolvePathType calls to satisfy SchemaTypeOptions constraints under exact optional semantics.
types/inferrawdoctype.d.ts	Same enum/undefined exclusion fix for ResolveRawPathType recursion.
types/inferhydrateddoctype.d.ts	Same enum/undefined exclusion fix for hydrated doc path inference recursion.
tstyche.json	Updates test file matching to include nested test/types/**/*.test.* files.
test/types/exactOptionalPropertyTypes/tsconfig.json	Adds a stricter TS config for this sub-suite (exactOptionalPropertyTypes: true, skipLibCheck: false).
test/types/exactOptionalPropertyTypes/exactOptionalPropertyTypes.test.ts	Adds a type test to ensure Mongoose’s .d.ts files type-check under the stricter config.

[mrazauskas]

It is more involving, but perhaps it is worth setting "exactOptionalPropertyTypes": true directly in test/types/tsconfig.json for all type tests? Code that compiles when "exactOptionalPropertyTypes" is enabled, would also compile when it is disabled.

I can do this next week (after my vacation).

[vkarpov15]

That seems reasonable. I'll merge this for now to unblock people.