fix: widen optional properties for exactOptionalPropertyTypes compati…

[maheshsingh20]

fix: widen optional properties for exactOptionalPropertyTypes compatibility

Summary

Fixes #65

Under TypeScript's exactOptionalPropertyTypes compiler flag, assigning undefined to an optional property whose declared type does not explicitly include undefined is a type error:

Type 'undefined' is not assignable to type 'Timeout'.

This is a type-only change — no runtime behavior is affected.

Changes

File	Property	Before	After
packages/include/src/index.ts	writeTask	NodeJS.Timeout	NodeJS.Timeout | undefined
packages/loader/src/config/entry.ts	_initTask	Promise<void>	Promise<void> | undefined
packages/core/src/context.ts	baseUrl	string	string | undefined

Details

All three properties are already marked optional (?) and are explicitly assigned undefined at various points in the codebase — so widening the type to include undefined is both correct and consistent.

While the original issue only reported writeTask in plugin-include, the same pattern was present in plugin-loader (_initTask) and core (baseUrl). All three are fixed here for consistency.

Consumer projects using "exactOptionalPropertyTypes": true in their tsconfig.json will no longer hit type errors when importing these packages.

Testing

No behavior change — this is purely a type annotation fix. The upstream build is unaffected since exactOptionalPropertyTypes is not enabled there. Consumer projects with the flag enabled will see the type errors resolved.

[maheshsingh20]

Apologies, closed this PR by mistake and reopened right away. PR is ready for review.