[gaxios] `undici-types` is not declared as dependency in package.json

[chrispisano-bc]

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Link to the code that reproduces this issue. A link to a public Github Repository or gist with a minimal reproduction.

https://github.com/chrispisano-bc/bare-bones-bazel

A step-by-step description of how to reproduce the issue, based on the linked reproduction.

Environment details

• OS: macOS 15.7.4 (24G517)
• Bazel with aspect_rules_ts 2.4.2
• aspect_rules_ts 3.6.3 (TypeScript project)
• Node/npm: 22.11.0
• pnpm 9.14.2

Steps to reproduce

1. Clone this repo: https://github.com/chrispisano-bc/bare-bones-bazel
2. read REPRODUCE.MD
3. Observe that the type checker cannot resolve undici-types: error TS2307: Cannot find module 'undici-types' or its corresponding type declarations.
4. Observe that if you install undici-types as a direct dependency or flip skipLibCheck to true, then the reproduce.js script no longer throws.

A clear and concise description of what the bug is, and what you expected to happen.

Description

undici-types is not declared as a direct/optional dependency in gaxios’s package.json, but the published type declarations use it. In packages/gaxios/src/common.ts (and in the emitted build/cjs/src/common.d.ts), the type is defined as:

type _BodyInit = typeof globalThis extends {BodyInit: infer T}
  ? T
  : import('undici-types').BodyInit;

In an isolated build environment (Bazel), this breaks the build if the associated tsconfig file has set skipLibCheck: false

Expected Result

Type-checking succeeds in isolated build environments. Gaxios should either declare undici-types as an optional/direct dependency or the published types should not reference it.

A clear and concise description WHY you expect this behavior, i.e., was it a recent change, there is documentation that points to this behavior, etc. **

I expect library types to compile even when skipLibCheck is set to false