stammtv-helper/base/popup/popup.js

function restore_options() {
    chrome.storage.local.get('baseURL', function (result) {
        if(result && result.baseURL.startsWith('http')) {
            document.getElementById('open-stammtv').href = result.baseURL;
        } else {
            openSettings();
        }
    });
}

function openSettings() {
    chrome.tabs.create({
        active: true,
        url: 'settings/settings.html'
    }, null);
}

document.addEventListener('DOMContentLoaded', restore_options);