Summary

This fixes an inconsistency between request interceptor option typing and the internal request interceptor handler typing.

Before this change:

• AxiosInterceptorOptions['runWhen'] was typed as (config: InternalAxiosRequestConfig) => boolean
• AxiosInterceptorManager['handlers'][number]['runWhen'] was typed differently in index.d.ts / index.d.cts

That mismatch can cause assignability issues when working with AxiosInstance types across module boundaries.

This patch:

• aligns AxiosInterceptorHandler['runWhen'] to AxiosInterceptorOptions['runWhen'] | null in both index.d.ts and index.d.cts
• adds typings coverage in both ESM and CJS typings tests to ensure handler and options runWhen types stay compatible

Fixes #7404.

Testing

• npm test --prefix test/module/typings/esm
• npm test --prefix test/module/typings/cjs

Summary by cubic

Aligns the interceptor handler runWhen type with AxiosInterceptorOptions to prevent assignability errors across module boundaries. Adds ESM and CJS typing tests to lock the contract.

Description

• Summary of changes
  • Set AxiosInterceptorHandler['runWhen'] to AxiosInterceptorOptions['runWhen'] | null in index.d.ts and index.d.cts.
  • Added minimal ESM/CJS typing tests asserting handler and options runWhen compatibility.
• Reasoning
  • Handler and option runWhen types diverged, causing type errors when sharing AxiosInstance types between modules.
• Additional context
  • Types-only change; no runtime behavior affected.
  • Fixes issue in runWhen types #7404.

Docs

No docs changes needed. This only aligns TypeScript typings.

Testing

• Added compile-time tests in:
  • test/module/typings/esm/index.ts
  • test/module/typings/cjs/index.ts
• How to run:
  • npm test --prefix test/module/typings/esm
  • npm test --prefix test/module/typings/cjs
• No runtime tests required for this types-only fix.

^{Written for commit 8ec423f. Summary will update on new commits.}