Fix: improve GetFilesResponse interface

[olishevskii]

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Fixes #2464 🦕

[ddelgrosso1]

Hi @olishevskii thank you for opening a PR and trying to clean this up.

If you take a look at

nodejs-storage/src/bucket.ts

Line 2840 in b4dbd73

nextQuery = Object.assign({}, query, {

you will see that what is actually being returned is a cross between GetFilesOptions & {pageToken?: string}. This PR omits the GetFilesOptions portion.

I'm also not sure we want to define a new interface that will need to be exported just to hold the page token portion.

[olishevskii]

Hi @ddelgrosso1.

I see your point of view regarding defining a new interface NextPageFilesOptions. I've rewritten my solution using TypeScript utilities. Additionally, I noticed that a query can be not only like GetFilesOptions but also like GetFilesCallback.

nodejs-storage/src/bucket.ts

Lines 2798 to 2802 in b4dbd73

	getFiles(
	queryOrCallback?: GetFilesOptions | GetFilesCallback,
	callback?: GetFilesCallback
	): void | Promise<GetFilesResponse> {
	let query = typeof queryOrCallback === 'object' ? queryOrCallback : {};

[ddelgrosso1]

You can omit GetFilesCallback, query can only be GetFilesOptions or an empty object. It will never get assigned the callback.

[olishevskii]

I have fixed it.