secretOrPrivateKey must be an asymmetric key when using RS256

* Operating System version: Ubuntu 22.10
* Firebase SDK version: 11.3.0
* Firebase Product: auth
* Node.js version: 16.13.2
* NPM version: 8.19.2

### [REQUIRED] Step 3: Describe the problem

I am using Firebase-Admin on a NestJs API, build with NX ; my API is using Admin SDK to create and manage users. For that, I am using the method auth.createUser({email, password}), but Firebase throws an error, ONLY FOR THE FIRST CALL :

`secretOrPrivateKey must be an asymmetric key when using RS256`

I know my private key is readed right, and most of all, only the first call to createUser returns error ; other calls are working great.. So I ended up putting a call with fake datas right after the initialization of Firebase, to be able to use it in other parts of my app, but it doesn't seem so terrible..! I can't find any other people having the same issue, really weird.

Any idea ?

Start by reproducing the first-call failure in auth.createUser using the listed Firebase Admin SDK and Node.js versions, then trace Firebase Auth initialization and the RS256 key handling. Done means identifying why only the first call rejects the asymmetric key and adding a regression test that verifies the first createUser call succeeds.

Written by the indexing model from the issue text.