I'm adapting a Chrome extension to Firefox. Eventhough https://www.extensiontest.com/ says my extension is compatible there are still errors.

One of them is the runtime.SendMessage function which I call in my content_script.js to send a message to background.js.

This method works as expected on Chrome/Brave but yield an uncaught exception: Object in Firefox.

chrome.runtime.sendMessage({
    type: "update-title",
    options: { title, url },
});

Looking at both API docs I cannot understand what's wrong for Firefox since they are supposed to be similar (Chrome docs, Firefox docs)