The payment step is blank or spins forever, how do you fix it?

A blank payment step or an endless spinner is nearly always a JavaScript error. We open the browser console first, a failed requirejs dependency, a payment-method renderer that throws, or a broken KnockoutJS template stops the whole step from rendering. We fix the failing component (not just hide the error) so payment methods render and the place-order button works, then test each enabled gateway.