fix(pubsub): align ClientConfig.port type with gax.GrpcClientOptions - #9539

🤖 I have created a release *beep* *boop*
---


<details><summary>google-gax: 6.11.1</summary>

##
[6.11.1](google-gax-v6.11.0...google-gax-v6.11.1)
(2026-10-06)


### Bug Fixes

* **gax:** Only set resend_count on T4 attempt spans
([#9540](#9540))
([3b3f600](3b3f600))
* **gax:** Widen port to number | string in GrpcClientOptions
([#9542](#9542))
([17978e7](17978e7))
</details>

<details><summary>pubsub: 6.1.1</summary>

##
[6.1.1](pubsub-v6.1.0...pubsub-v6.1.1)
(2026-10-06)


### Bug Fixes

* **pubsub:** Align ClientConfig.port type with gax.GrpcClientOptions
([#9539](#9539))
([4443d6d](4443d6d))
* **test-utils:** Make google-test-utils a private workspace package
([#9525](#9525))
([be25b6f](be25b6f))
</details>

---
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Reverts PR #9539 as to not break customers.

The `port` type definition was expanded in PR#3542 as a non-breaking
change.

---------

Co-authored-by: Santiago Quiroga <[email protected]>

…ent_ (#9544)

## Description

Replaces the `.then().catch()` promise chain and
`promise/no-callback-in-promise` ESLint disable comments in
`PubSub.prototype.getClient_` with an `async` IIFE and `try / catch`
block.

## Impact

Prevents synchronous errors thrown inside the `getClient_` callback from
being caught by `.catch(callback)` and invoking the callback a second
time, while satisfying `eslint-plugin-promise` rules without lint
suppressions (follow-up to #9539).

## Changes

- Refactored `PubSub.prototype.getClient_` in
`handwritten/pubsub/src/pubsub.ts` to `await
this.getClientAsync_(config)` inside a `try / catch` block within a
`void (async () => { ... })()` IIFE and invoke `callback(null, client)`
outside the `try / catch` block.
- Removed the two `// eslint-disable-next-line
promise/no-callback-in-promise` comments in
`handwritten/pubsub/src/pubsub.ts`.

## Testing

- Verified existing `getClient_` and `request` unit tests in
`handwritten/pubsub/test/pubsub.ts` pass (`105 passing`).
- Verified `GIT_DIFF_ARG=upstream/main node ./bin/linter.mjs --strict`
passes with zero ESLint errors or warnings and passes TypeScript type
checking.

## Alternatives

- Keep the `.then().catch()` chain with `eslint-disable-next-line
promise/no-callback-in-promise` comments: rejected because if
`callback(null, client)` throws synchronously, `.catch(callback)`
catches that error and invokes `callback` a second time.