Firefox (Mac latest version) redirecting

Click on most any navigation link and the visitor is automatically forwarded to a page that doesn’t exist. For example: Click on “CONTACT” and Firefox will take briefly to https://braintracksaudio.com/contact but then immediately redirects to https://braintracksaudio.com/contact/calendar.js. Or hover over COACHING and click “GROUP” and it briefly goes to https://braintracksaudio.com/coaching/group before redirecting to https://braintracksaudio.com/coaching/group/calendar/calendar.js.

Help?