Firebase auth with LOCAL persistence not working from a Worker context

[raphaelbs]

[REQUIRED] Describe your environment

• Operating System version: Ubuntu 19.04
• Browser version: Chrome Version 81.0.4044.92 (Official Build) (64-bit)
• Firebase SDK version: 7.12.0
• Firebase Product: auth

[REQUIRED] Describe the problem

Steps to reproduce:

While using firebase auth within a web worker, with persistence set to firebase.auth.Auth.Persistence.LOCAL, console is logging the UNSUPPORTED_PERSISTENCE error: The current environment does not support the specified persistence type.

Relevant Code:

Debugging the firebase code, the problem seems to be caused by isWebStorageSupported method, because it checks for localStorage before running the try/catch block but, as the Worker doesn't have localStorage, it goes directly into the return statement:

// worker.js

const auth = firebase.app().auth();
auth.setPersistence(firebase.auth.Auth.Persistence.LOCAL)
        .then(() => auth.signInWithCustomToken(token));

[raphaelbs]

@thebrianchen the auth should work or it also depends on localStorage?

[bojeil-google]

Local persistence is the default for a worker environment. In a worker environment, indexedDB is used. You don't even need to specify it. Can you try again without specifying it? If that works, we can fix this so it works when it is explicitly specified in that environment.

[raphaelbs]

It worked indeed! Thank you so much for the quick response @bojeil-google!

It would be great if this information was linked somewhere in the docs e.g.
https://firebase.google.com/docs/auth/web/auth-state-persistence

[bojeil-google]

Let's keep this open. I will send a quick fix to fix this.