TypeError: Right-hand side of 'instanceof' is not an object about msw

[dsanch3z]

I was getting a very similar error and was able to solve it, I hope this helps.

Make sure you add all the polyfills needed as mentioned here: https://mswjs.io/docs/migrations/1.x-to-2.x#requestresponsetextencoder-is-not-defined-jest. I did the same but I started getting Right-hand side of 'instanceof' is not an object as an error so I just added ReadableStream to the setup file and the tests are running fine now, this is how my setup tests file looks like:

const { TextDecoder, TextEncoder } = require("node:util");
const { ReadableStream } = require("node:stream/web");

Object.defineProperties(globalThis, {
  TextDecoder: { value: TextDecoder },
  TextEncoder: { value: TextEncoder },
  ReadableStream: { value: ReadableStream },
});

const { Blob, File } = require("node:buffer");
const { fetch, Headers, FormData, Request, Response } = require("undici");

Object.defineProperties(globalThis, {
  fetch: { value: fetch, writable: true },
  Blob: { value: Blob },
  File: { value: File },
  Headers: { value: Headers },
  FormData: { value: FormData },
  Request: { value: Request },
  Response: { value: Response },
});

[BrunoQuaresma]

Fixed by #2082

[BrunoQuaresma]

It was partially solved but still happening for a few tests.

[BrunoQuaresma]

This worked!!! Thanks A LOT @dsanch3z