Naked domain shows error in browser, but correctly forwards to the www domain after a few seconds

Web developers I have a question for you.

My website's domain is www.damadam.in, naked domain being damadam.in. Sometimes, when I type the naked domain in the address bar of Chrome, it gives me the error shown below. Yet the browser keeps on loading (I see a spinning wheel in Chrome's tab above the URL bar) and after a bit, www.damadam.in loads.

How can I prevent this error from appearing?

Mine is a simple Heroku web app. I'm not utilizing anything beyond Heroku's free dyno at the moment, which means the app goes to sleep after 10 mins of inactivity and has to sleep a fixed number of hours every day. If there's a lag in accessing the app, that's because the app is waking up. The error above probably appears while the app is waking up.

FYI my Heroku app is at damadam.herokuapp.com. I bought www.damadam.in from GoDaddy, and added a CName (Alias) with host www that points to damadam.herokuapp.com. I also set up forwarding on damadam.in to forward traffic permanently to www.damadam.in. Lastly, I added www.damadam.in and damadam.in both to my Heroku app via heroku add:domains www.damadam.in and heroku add:domains damadam.in

BTW, everything is over HTTP; I don't have an SSL certificate installed at the moment.