Fetch options are overridden on parallel requests

[vakrilov]

Describe the issue you're facing

On multiple parallel requests to the API are made (so that the client throttling is triggered) the the fetch params are not passed correctly to the fetch function.

Looks like the reason this happens is that fetchOptions are preserved in the SbFetch instance and then used when calling fetch.

Reproduction

https://stackblitz.com/edit/stackblitz-starters-xkyznv?file=index.js

Steps to reproduce

Here is a short example using node. I've added a custom fetch wrapper to observe the passed parameters:

import { storyblokInit, apiPlugin } from "@storyblok/js";

const { storyblokApi } = storyblokInit({
  accessToken: "XXXXXXX",
  use: [apiPlugin],
  apiOptions: {
    rateLimit: 2, // reduced to 2 for simplicity
    fetch: (url, params) => {
      console.log(`Fetch params.next.tag: ${params?.next?.tags}`);
      return fetch(url, params);
    },
  },
});

const slugs = ["slug1", "slug2", "slug3", "slug4", "slug5"];

await Promise.allSettled(
  slugs.map((slug) =>
    storyblokApi.get(`cdn/stories/${slug}`, {}, { next: { tags: [slug] } })
  )
);

Output (after rateLimit is triggered all subsequent fetch calls have the params of the last get) :

Fetch params.next.tag: slug1
Fetch params.next.tag: slug2
Fetch params.next.tag: slug5
Fetch params.next.tag: slug5
Fetch params.next.tag: slug5

Expected Output:

Fetch params.next.tag: slug1
Fetch params.next.tag: slug2
Fetch params.next.tag: slug3
Fetch params.next.tag: slug4
Fetch params.next.tag: slug5

System Info

System:
    OS: macOS 14.5
    CPU: (10) arm64 Apple M1 Max
    Memory: 3.22 GB / 64.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 18.19.1 - ~/.asdf/installs/nodejs/18.19.1/bin/node
    Yarn: 1.22.19 - /usr/local/bin/yarn
    npm: 10.2.4 - ~/.asdf/plugins/nodejs/shims/npm
    pnpm: 9.4.0 - /usr/local/bin/pnpm
  Browsers:
    Chrome: 127.0.6533.88
    Safari: 17.5

Used Package Manager

npm

Error logs (Optional)

No response

Validations

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[vakrilov]

To add more context, I'm using the fetchOptions to configure revalidation tags in a NextJS application.
With this issue - when statically building the application there are multiple requests to the Storyblok API, however they all end up with the same tag instead of different ones.

The workaround for now is to create a new client (with storyblokInit) for each request so that it has separate SbFetch instance and separate fetchOptions.