function getUrlHistory() {
    const STORAGE_KEY = 'ghost-history';

    try {
        const historyString = localStorage.getItem(STORAGE_KEY);
        if (historyString) {
            const parsed = JSON.parse(historyString);

            if (Array.isArray(parsed)) {
                return parsed;
            }
        }
    } catch (error) {
        // Failed to access localStorage or something related to that.
        // Log a warning, as this shouldn't happen on a modern browser.

        /* eslint-disable no-console */
        console.warn(`[Portal] Failed to load member URL history:`, error);
    }
}
Returns the member attribution URL history, which is stored in localStorage, if there is any.
@warning If you make changes here, please also update the one in signup-form!
@returns {Object[]|undefined}