I'm afraid I can't really say what's wrong with your theme. The code I posted above was an illustrative example of some testing I did and I haven't found a solution myself. Seems like a Shopify bug to me.

Now that the new design experience is starting to roll out I've noticed an issue with one of our apps that I believe must be a bug with the new theme customizer:When you're customizing your theme with the new customizer you can redirect to a page wit...