I can't use the browser object from the settings page of my Firefox add-on

Question

I'm making a Firefox Add-On that needs to keep track of a list of words. From the main javascript file I can read and modify a stored Array under the name "list", but when I try to access it from the settings page I get an error:

ReferenceError: browser is not defined

Here is the function from which I try to access the local storage (this is in the .js file that is used in my .html settings page).

function EmptyList() {
    if (confirm("Empty list?")){
    browser.storage.local.set({
        list : []
    });
    }
}

I don't understand what am I doing wrong. I'm not doing anything different from what they do in the mozilla tutorial .

Answer 1

Apparently it has something to do with the cache.

Disable and reenable the add-on (or remove it and add it again) and it works. Go figure.