urbit-browser-manager/extension/background/main.js

const browser = require("webextension-polyfill");
console.log("Executing Urbit extension background main script");

browser.storage.sync.get("credentials")
    .then((result) => {
        console.log(result);
        if (result.credentials && result.credentials.urbitId && result.credentials.urbitCode) {
            console.log("Creds:");
            console.log(result.credentials);
        } else {
            console.log("Couldn't find credentials");
        }
    });